Fixes vttestserver to work with sharded keyspaces

[GuptaManan100]

Description

Adds vschema to the vttestserver image so that it works correcly for the sharded keyspaces too. It also authorizes all users for ddl commands

• we need vschema_ddl_authorized_users flag to run vschema commands
• Earlier we could setup the number of shards via num_shards flag, but we weren’t setting up the vschema which led to a wierd problem. When I ran create table t1 I got the error Keyspace does not have exactly one shard: [0xc000513100 0xc000513120] This happened because the vschema was not setup and the vtgate assumed that the keyspace was unsharded. This PR fixes it by setting up a minimalistic vschema whenever the number of shards are more than 1.

Related Issue(s)

• Run all Rails tests in sharded mode planetscale/vitess-framework-testing#125

Checklist

• Should this PR be backported?
• Tests were added or are not required Not Required
• Documentation was added or is not required Not Required

Impacted Areas in Vitess

Components that this PR will affect:

• Query Serving
• VReplication
• Cluster Management
• Build/CI
• VTAdmin

[deepthi]

How do you feel about writing a CI test for this that runs in docker?
Right now we have a unit test (in go/cmd/vttestserver) and an endtoend test (vttest_sample). Neither of them runs in docker.

[GuptaManan100]

@deepthi I can add the CI test as part of a separate PR. Could we merge this for now?

[deepthi]

@deepthi I can add the CI test as part of a separate PR. Could we merge this for now?

That is acceptable.

[deepthi]

LGTM

[GuptaManan100]

@deepthi Added end to end tests for the docker image in #8210