[APPSEC-56683] Add appsec.auto_user_instrumentation.mode setting

[Strech]

What does this PR do?

Adds a new customer-facing setting for AppSec which is suppose to replace existing deprecated option. It will not take precedence over existing setting, but since new and old settings is an explicit opt-out, as soon as any of them set to disabled, the feature will be disabled.

Motivation:

This is a part of the automated user tracking functionality.

Change log entry

Yes. AppSec: Deprecate appsec.track_user_events configuration setting in favor of appsec.auto_user_instrumentation.

Additional Notes:

This setting immediately will be incorporated into existing code, so it will be fine to release it without an additional functionality.

How to test the change?

CI should be enough

[datadog-datadog-prod-us1]

Datadog Report

Branch report: appsec-56683-update-auto-user-instrumentation-mode-configuration
Commit report: 18e933f
Test service: dd-trace-rb

✅ 0 Failed, 22090 Passed, 1477 Skipped, 5m 43.45s Total Time

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 99.58848% with 2 lines in your changes missing coverage. Please review.

Project coverage is 97.73%. Comparing base (5c1cea4) to head (18e933f).

Files with missing lines	Patch %	Lines
lib/datadog/appsec/contrib/devise/configuration.rb	92.85%	1 Missing ⚠️
...ec/contrib/devise/patcher/authenticatable_patch.rb	93.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4352      +/-   ##
==========================================
- Coverage   97.73%   97.73%   -0.01%     
==========================================
  Files        1348     1351       +3     
  Lines       82511    82681     +170     
  Branches     4199     4197       -2     
==========================================
+ Hits        80646    80810     +164     
- Misses       1865     1871       +6     

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[pr-commenter]

Benchmarks

Benchmark execution time: 2025-02-11 10:23:21

Comparing candidate commit 18e933f in PR branch appsec-56683-update-auto-user-instrumentation-mode-configuration with baseline commit 5c1cea4 in branch master.

Found 1 performance improvements and 0 performance regressions! Performance is the same for 30 metrics, 2 unstable metrics.

scenario:profiler - sample timeline=false

• 🟩 throughput [+0.512op/s; +0.524op/s] or [+8.721%; +8.929%]