fix: ensure deprecated flags are correctly hidden

[raulb]

Description

Fixes #1971

The Flags() method on entrypoint.go is used in different places, and this pull-requests ensure that both the usage by this method and when using via the main Conduit CLI is correctly set.

Added unit tests to avoid regressions.

Before

Conduit CLI is a command-line that helps you interact with and manage Conduit.

Usage:
  conduit [flags]
  conduit [command]

Pipelines
  pipelines   Initialize and manage pipelines

Additional Commands:
  help        Help about any command
  init        Initialize Conduit with a configuration file and directories.

Flags:
      --api.enabled                                            enable HTTP and gRPC API (default true)
      --connectors.path string                                 path to standalone connectors' directory (default "/Users/rb/code/conduitio/conduit/connectors")
      --db.badger.path string                                  path to badger DB (default "/Users/rb/code/conduitio/conduit/conduit.db")
      --db.postgres.connection-string string                   postgres connection string, may be a database URL or in PostgreSQL keyword/value format
      --db.postgres.table string                               postgres table in which to store data (will be created if it does not exist) (default "conduit_kv_store")
      --db.sqlite.path string                                  path to sqlite3 DB (default "/Users/rb/code/conduitio/conduit/conduit.db")
      --db.sqlite.table string                                 sqlite3 table in which to store data (will be created if it does not exist) (default "conduit_kv_store")
      --db.type string                                         database type; accepts badger,postgres,inmemory,sqlite (default "badger")
      --dev                                                    used together with the dev flag it shows dev flags
      --dev.blockprofile string                                write block profile to file
      --dev.cpuprofile string                                  write cpu profile to file
      --dev.memprofile string                                  write memory profile to file
      --grpc.address string                                    address for serving the gRPC API (default ":8084")
  -h, --help                                                   help for conduit
      --http.address string                                    address for serving the HTTP API (default ":8080")
      --log.format string                                      sets the format of the logging; accepts json, cli (default "cli")
      --log.level string                                       sets logging level; accepts debug, info, warn, error, trace (default "info")
      --pipelines.error-recovery.backoff-factor int            backoff factor applied to the last delay (default 2)
      --pipelines.error-recovery.max-delay duration            maximum delay before restart (default 10m0s)
      --pipelines.error-recovery.max-retries int               maximum number of retries (default -1)
      --pipelines.error-recovery.max-retries-window duration   amount of time running without any errors after which a pipeline is considered healthy (default 5m0s)
      --pipelines.error-recovery.min-delay duration            minimum delay before restart (default 1s)
      --pipelines.exit-on-degraded                             exit Conduit if a pipeline enters a degraded state
      --pipelines.exit-on-error exit-on-degraded               Deprecated: use exit-on-degraded instead.
                                                               exit Conduit if a pipeline experiences an error while running
      --pipelines.path string                                  path to the directory that has the yaml pipeline configuration files, or a single pipeline configuration file (default "/Users/rb/code/conduitio/conduit/pipelines")
      --preview.pipeline-arch-v2                               enables experimental pipeline architecture v2 (note that the new architecture currently supports only 1 source and 1 destination per pipeline)
      --processors.path string                                 path to standalone processors' directory (default "/Users/rb/code/conduitio/conduit/processors")
      --schema-registry.confluent.connection-string string     confluent schema registry connection string
      --schema-registry.type string                            schema registry type; accepts builtin,confluent (default "builtin")
  -v, --version                                                version for conduit

Use "conduit [command] --help" for more information about a command.

After

Conduit CLI is a command-line that helps you interact with and manage Conduit.

Usage:
  conduit [flags]
  conduit [command]

Pipelines
  pipelines   Initialize and manage pipelines

Additional Commands:
  help        Help about any command
  init        Initialize Conduit with a configuration file and directories.

Flags:
      --api.enabled                                            enable HTTP and gRPC API (default true)
      --connectors.path string                                 path to standalone connectors' directory (default "/Users/rb/code/conduitio/conduit/connectors")
      --db.badger.path string                                  path to badger DB (default "/Users/rb/code/conduitio/conduit/conduit.db")
      --db.postgres.connection-string string                   postgres connection string, may be a database URL or in PostgreSQL keyword/value format
      --db.postgres.table string                               postgres table in which to store data (will be created if it does not exist) (default "conduit_kv_store")
      --db.sqlite.path string                                  path to sqlite3 DB (default "/Users/rb/code/conduitio/conduit/conduit.db")
      --db.sqlite.table string                                 sqlite3 table in which to store data (will be created if it does not exist) (default "conduit_kv_store")
      --db.type string                                         database type; accepts badger,postgres,inmemory,sqlite (default "badger")
      --dev.blockprofileblockprofile string                    write block profile to file
      --dev.cpuprofile string                                  write cpu profile to file
      --dev.memprofile string                                  write memory profile to file
      --grpc.address string                                    address for serving the gRPC API (default ":8084")
  -h, --help                                                   help for conduit
      --http.address string                                    address for serving the HTTP API (default ":8080")
      --log.format string                                      sets the format of the logging; accepts json, cli (default "cli")
      --log.level string                                       sets logging level; accepts debug, info, warn, error, trace (default "info")
      --pipelines.error-recovery.backoff-factor int            backoff factor applied to the last delay (default 2)
      --pipelines.error-recovery.max-delay duration            maximum delay before restart (default 10m0s)
      --pipelines.error-recovery.max-retries int               maximum number of retries (default -1)
      --pipelines.error-recovery.max-retries-window duration   amount of time running without any errors after which a pipeline is considered healthy (default 5m0s)
      --pipelines.error-recovery.min-delay duration            minimum delay before restart (default 1s)
      --pipelines.exit-on-degraded                             exit Conduit if a pipeline enters a degraded state
      --pipelines.path string                                  path to the directory that has the yaml pipeline configuration files, or a single pipeline configuration file (default "/Users/rb/code/conduitio/conduit/pipelines")
      --preview.pipeline-arch-v2                               enables experimental pipeline architecture v2 (note that the new architecture currently supports only 1 source and 1 destination per pipeline)
      --processors.path string                                 path to standalone processors' directory (default "/Users/rb/code/conduitio/conduit/processors")
      --schema-registry.confluent.connection-string string     confluent schema registry connection string
      --schema-registry.type string                            schema registry type; accepts builtin,confluent (default "builtin")
  -v, --version                                                version for conduit

Use "conduit [command] --help" for more information about a command.

Quick checks

• I have followed the Code Guidelines.
• There is no other pull request for the same update/change.
• I have written unit tests.
• I have made sure that the PR is of reasonable size and can be easily reviewed.