Move apm-idm-ruby ownership to tracing-ruby

[marcotc]

The bus factor is too low for apm-idm-ruby today.
With only two members:

• A PR from one of the two members HAS to be approved by the other; no replacement reviewer qualifies. If one member is away, the other cannot merge their work.
• If both members are away, no PR touching tracing/contrib can be merged.

This PR changes the ownership of tracing/contrib files to tracing-ruby, which has four members and already owns tracing and opentelemetry. The members tracing-ruby are: both apm-idm-ruby members plus two other very smart and handsome Ruby engineers.

Change log entry
No

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.76%. Comparing base (afad677) to head (58da147).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4542   +/-   ##
=======================================
  Coverage   97.76%   97.76%           
=======================================
  Files        1392     1392           
  Lines       84973    84972    -1     
  Branches     4285     4285           
=======================================
  Hits        83077    83077           
+ Misses       1896     1895    -1     

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[datadog-datadog-prod-us1]

Datadog Report

Branch report: marcotc/tracing-owners
Commit report: 58da147
Test service: dd-trace-rb

✅ 0 Failed, 20785 Passed, 1373 Skipped, 3m 15.33s Total Time

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-03-27 21:44:17

Comparing candidate commit 58da147 in PR branch marcotc/tracing-owners with baseline commit afad677 in branch master.

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