[SqlClient] Stop Activity.Current if present

[martincostello]

Fixes #3033

Changes

Ensure any current activity is stopped if only metrics is enabled but a global activity listener is registered.

I've manually verified the original issue is resolved and that .NET isn't affected by the same issue.

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

❌ Patch coverage is 80.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.89%. Comparing base (7adf24a) to head (fc92d32).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...ent/Implementation/SqlEventSourceListener.netfx.cs	80.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3041      +/-   ##
==========================================
+ Coverage   69.78%   69.89%   +0.11%     
==========================================
  Files         420      410      -10     
  Lines       16294    16242      -52     
==========================================
- Hits        11371    11353      -18     
+ Misses       4923     4889      -34     

Flag	Coverage Δ
unittests-Instrumentation.Cassandra	?
unittests-Instrumentation.SqlClient	86.92% <80.00%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ent/Implementation/SqlEventSourceListener.netfx.cs	81.08% <80.00%> (-0.17%)	⬇️

... and 13 files with indirect coverage changes

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[Copilot]

Pull Request Overview

This PR fixes an issue where SQL activities were not being properly stopped on .NET Framework when using a global activity listener with metrics-only configuration. The change ensures that any current SQL activity is stopped regardless of whether tracing or metrics are being collected.

• Separates activity stopping logic from activity modification logic in the event handler
• Adds comprehensive test coverage for the metrics-only scenario with global activity listener
• Updates changelog to document the bug fix

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
SqlEventSourceListener.netfx.cs	Refactors OnEndExecute method to ensure SQL activities are stopped even when only metrics are enabled
SqlClientIntegrationTests.cs	Adds test to verify activities are properly stopped in metrics-only scenarios and minor code cleanup
CHANGELOG.md	Documents the bug fix for activity stopping issue

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