Update OpenSearch resource names to be relative instead of full path

[sarahchen6]

What does this PR do?
This PR updates OpenSearch resource names to use relative paths, instead of full paths, similar to how ElasticSearch does.

Motivation:
Resolve customer issue migrating from ElasticSearch to OpenSearch: #4474

Change log entry
Yes. Tracing: Update OpenSearch integration to include a feature flag for resource names. By default and with the existing implementation, the resource name is set to the full URL path; however, now resource names can instead be set to use relative paths.

Additional Notes:

How to test the change?
Tested through unit tests (bundle exec rspec spec/datadog/tracing/contrib/opensearch/patcher_spec.rb).

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-03-20 14:59:13

Comparing candidate commit 8c436bc in PR branch sarahchen6/update-opensearch-resource-names with baseline commit 7d88b81 in branch master.

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

[datadog-datadog-prod-us1]

Datadog Report

Branch report: sarahchen6/update-opensearch-resource-names
Commit report: 8c436bc
Test service: dd-trace-rb

✅ 0 Failed, 20792 Passed, 1370 Skipped, 3m 15.29s Total Time

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.74%. Comparing base (7d88b81) to head (8c436bc).
Report is 40 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4509      +/-   ##
==========================================
+ Coverage   97.70%   97.74%   +0.04%     
==========================================
  Files        1381     1388       +7     
  Lines       83973    84659     +686     
  Branches     4251     4276      +25     
==========================================
+ Hits        82043    82752     +709     
+ Misses       1930     1907      -23     

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