[Exporter.Geneva] Update mapping for http tags

[utpilla]

Changes

• Update mapping for http tags based on the new semantic conventions

https://github.com/open-telemetry/opentelemetry-dotnet/blob/main/src/Shared/SemanticConventions.cs#L120-L121

https://github.com/open-telemetry/opentelemetry-dotnet/blob/main/src/Shared/SemanticConventions.cs#L126

For significant contributions please make sure you have completed the following items:

• Appropriate CHANGELOG.md updated for non-trivial changes

[codecov]

Codecov Report

Merging #1402 (ecf0fbe) into main (71655ce) will decrease coverage by 15.79%.
Report is 30 commits behind head on main.
The diff coverage is 36.84%.

@@             Coverage Diff             @@
##             main    #1402       +/-   ##
===========================================
- Coverage   73.91%   58.13%   -15.79%     
===========================================
  Files         267       29      -238     
  Lines        9615     3036     -6579     
===========================================
- Hits         7107     1765     -5342     
+ Misses       2508     1271     -1237     

Flag	Coverage Δ
unittests-Exporter.Geneva	58.13% <36.84%> (?)

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

Files	Coverage Δ
...orter.Geneva/MsgPackExporter/MsgPackLogExporter.cs	95.10% <100.00%> (+1.76%)	⬆️
...ter.Geneva/MsgPackExporter/MsgPackTraceExporter.cs	94.52% <100.00%> (+2.10%)	⬆️
...ry.Exporter.Geneva/TLDExporter/TldTraceExporter.cs	33.33% <30.00%> (+1.01%)	⬆️
...etry.Exporter.Geneva/TLDExporter/TldLogExporter.cs	28.38% <0.00%> (-8.73%)	⬇️

... and 243 files with indirect coverage changes