[Instrumentation.Http] Skip tagging traces when running on .NET 9+

[TimothyMothra]

Fixes #2029

Net9 added support for Http semantic convention attributes here: dotnet/runtime#104251

Changes

• update Instrumentation.Http to not override tags set by NET9.
• update unit tests

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

All modified and coverable lines are covered by tests ✅

Project coverage is 67.96%. Comparing base (71655ce) to head (d65b138).
Report is 616 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2314      +/-   ##
==========================================
- Coverage   73.91%   67.96%   -5.95%     
==========================================
  Files         267      363      +96     
  Lines        9615    13512    +3897     
==========================================
+ Hits         7107     9184    +2077     
- Misses       2508     4328    +1820     

Flag	Coverage Δ
unittests-Instrumentation.Http	74.33% <100.00%> (?)

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

Files with missing lines	Coverage Δ
...tp/Implementation/HttpHandlerDiagnosticListener.cs	72.95% <100.00%> (ø)

... and 386 files with indirect coverage changes

[alanwest]

PR looks pretty good, but looks like there's some build issues.

[TimothyMothra]

PR looks pretty good

Thanks!

but looks like there's some build issues.

Sigh. Visual Studio keeps saving files with Windows line endings (CR LF), but this repo expects Unix line endings (LF).
I haven't found a way to force Visual Studio to stop changing things. 🤦‍♂️

[CodeBlanch]

LGTM