Update build files for integration tests

[utpilla]

Changes

• Update .sln file to include docker compose file for net6.0
• Remove docker compose file for net5.0

[codecov]

Codecov Report

Merging #3347 (ebf844c) into main (a209aa3) will increase coverage by 0.23%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #3347      +/-   ##
==========================================
+ Coverage   85.24%   85.47%   +0.23%     
==========================================
  Files         270      270              
  Lines        9561     9561              
==========================================
+ Hits         8150     8172      +22     
+ Misses       1411     1389      -22     

Impacted Files	Coverage Δ
...ZPages/Implementation/ZPagesExporterEventSource.cs	56.25% <0.00%> (-6.25%)	⬇️
...heus/Implementation/PrometheusCollectionManager.cs	82.27% <0.00%> (+2.53%)	⬆️
...metryProtocol/Implementation/ActivityExtensions.cs	94.50% <0.00%> (+3.29%)	⬆️
...xporter.OpenTelemetryProtocol/OtlpTraceExporter.cs	77.27% <0.00%> (+40.90%)	⬆️
...entation/ExportClient/OtlpGrpcTraceExportClient.cs	78.57% <0.00%> (+42.85%)	⬆️