fix(datadog-headers): ignore invalid tid values in x-datadog-tags

[mabdinur]

What does this PR do?

• Ensures only 16 character hexadecimals are extracted from the _dd.p.tid distributed tracing tag. This ensures the ruby tracer does not propagate invalid/unexpected trace ids.

Motivation:

• Ensure the ruby tracer propagates 128bit trace ids in a manner that is consistent with other datadog libraries.

Change log entry

Ensures the Ruby tracer extracts only 16-character hex values from the _dd.p.tid tag in x-datadog-tags, preventing invalid trace ID propagation.

Additional Notes:

How to test the change?

[github-actions]

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^{Visited at: 2025-03-24 14:50:17 UTC}

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.75%. Comparing base (535244c) to head (855b4ab).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4534      +/-   ##
==========================================
- Coverage   97.76%   97.75%   -0.02%     
==========================================
  Files        1390     1390              
  Lines       84748    84762      +14     
  Branches     4281     4283       +2     
==========================================
+ Hits        82856    82861       +5     
- Misses       1892     1901       +9     

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[datadog-datadog-prod-us1]

Datadog Report

Branch report: munir/fix-128-trace-id-validations
Commit report: 855b4ab
Test service: dd-trace-rb

✅ 0 Failed, 21007 Passed, 1370 Skipped, 3m 13.12s Total Time

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-03-24 18:25:22

Comparing candidate commit 855b4ab in PR branch munir/fix-128-trace-id-validations with baseline commit 535244c in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 31 metrics, 2 unstable metrics.