fix: remove version tag if dd_service is not applied

[mabdinur]

What does this PR do?

• Ensures the trace level version tag is only applied to spans that use the global/default service name. This will keep DD_SERVICE and DD_VERSION insync

Motivation:

• Parity with other tracing clients

Failing system-test: https://github.com/DataDog/system-tests/blob/5e90616079fc11656348026f5f771aea8bafa748/tests/parametric/test_config_consistency.py#L92

Change log entry

Additional Notes:

How to test the change?

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 94.11765% with 1 line in your changes missing coverage. Please review.

Project coverage is 97.85%. Comparing base (91d883f) to head (a8025b1).

Files with missing lines	Patch %	Lines
lib/datadog/tracing/tracer.rb	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4027      +/-   ##
==========================================
- Coverage   97.86%   97.85%   -0.01%     
==========================================
  Files        1321     1321              
  Lines       79326    79336      +10     
  Branches     3934     3936       +2     
==========================================
+ Hits        77631    77636       +5     
- Misses       1695     1700       +5     

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[pr-commenter]

Benchmarks

Benchmark execution time: 2024-10-24 20:25:28

Comparing candidate commit a8025b1 in PR branch munir/remove-version-tag-in-some-scenarios with baseline commit 91d883f in branch master.

Found 1 performance improvements and 0 performance regressions! Performance is the same for 23 metrics, 2 unstable metrics.

scenario:profiler - sample timeline=false

• 🟩 throughput [+0.451op/s; +0.465op/s] or [+7.231%; +7.450%]