[Http] Fix propagation issues

[CodeBlanch]

Changes

I was working on tests for #3793 and it seems we have a propagation bug:

• On .NET 7 our new rule to exclude the legacy activity skips our propagation completely when span is not sampled.

What this change does is...

• Restore that propagation always happens.

TODOs

• Appropriate CHANGELOG.md updated for non-trivial changes

[codecov]

Codecov Report

Merging #3828 (2cfd787) into main (1a65aec) will decrease coverage by 0.29%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3828      +/-   ##
==========================================
- Coverage   87.42%   87.13%   -0.30%     
==========================================
  Files         280      280              
  Lines       10767    10765       -2     
==========================================
- Hits         9413     9380      -33     
- Misses       1354     1385      +31     

Impacted Files	Coverage Δ
...tp/Implementation/HttpHandlerDiagnosticListener.cs	73.68% <100.00%> (+0.48%)	⬆️
...entation/ExportClient/OtlpGrpcTraceExportClient.cs	35.71% <0.00%> (-42.86%)	⬇️
...xporter.OpenTelemetryProtocol/OtlpTraceExporter.cs	46.15% <0.00%> (-34.62%)	⬇️
src/OpenTelemetry/Logs/Pool/LogRecordSharedPool.cs	78.94% <0.00%> (-21.06%)	⬇️
...emetry.Api/Internal/OpenTelemetryApiEventSource.cs	73.52% <0.00%> (-8.83%)	⬇️
...metryProtocol/Implementation/ActivityExtensions.cs	91.89% <0.00%> (-4.33%)	⬇️
...Telemetry/Internal/SelfDiagnosticsEventListener.cs	97.65% <0.00%> (+0.78%)	⬆️
...Propagators/OpenTelemetryPropagatorsEventSource.cs	100.00% <0.00%> (+12.50%)	⬆️

[alanwest]

For test case sample == true && createParentActivity == true shouldn't we expect nothing exported?

That is, the parent activity that is created is not sampled, right? So per the default ParentBasedSampler LocalParentNotSampled sampler defaults to AlwaysOff.

[CodeBlanch]

That is, the parent activity that is created is not sampled, right?

It is fake sampled 🤣

   parent = new Activity("parent")
      .SetIdFormat(ActivityIdFormat.W3C)
      .Start();

   parent.TraceStateString = "k1=v1,k2=v2";
   parent.ActivityTraceFlags = ActivityTraceFlags.Recorded; // <- Here