[Examples] Remove log scope

[martincostello]

Fixes #6877 (review).

Changes

Remove log scope from ASP.NET Core example.

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)

[Copilot]

Pull request overview

Removes an unnecessary logging scope from the ASP.NET Core example controller to simplify the sample and avoid adding extra structured scope state to each request.

Changes:

• Removed per-request BeginScope usage from WeatherForecastController.Get.
• Deleted the associated LoggerMessage.DefineScope helper from the nested Logger class.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.25%. Comparing base (6180ae3) to head (d13462c).
⚠️ Report is 3 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6880      +/-   ##
==========================================
+ Coverage   87.22%   87.25%   +0.03%     
==========================================
  Files         263      263              
  Lines       12385    12385              
==========================================
+ Hits        10803    10807       +4     
+ Misses       1582     1578       -4     

Flag	Coverage Δ
unittests-Project-Experimental	87.06% <ø> (+0.04%)	⬆️
unittests-Project-Stable	87.00% <ø> (-0.15%)	⬇️

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see 4 files with indirect coverage changes