Remove StackExchangeRedis instrumentation

[utpilla]

Towards #3317

StackExchangeRedis instrumentation has moved to contrib repo: https://github.com/open-telemetry/opentelemetry-dotnet-contrib/tree/main/src/OpenTelemetry.Instrumentation.StackExchangeRedis

Changes

• Remove StackExchangeRedis instrumentation

[codecov]

Codecov Report

Merging #3346 (9861830) into main (8df82a2) will increase coverage by 0.15%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #3346      +/-   ##
==========================================
+ Coverage   85.47%   85.62%   +0.15%     
==========================================
  Files         270      266       -4     
  Lines        9561     9370     -191     
==========================================
- Hits         8172     8023     -149     
+ Misses       1389     1347      -42     

Impacted Files	Coverage Δ
...entation/ExportClient/OtlpGrpcTraceExportClient.cs	35.71% <0.00%> (-42.86%)	⬇️
...xporter.OpenTelemetryProtocol/OtlpTraceExporter.cs	36.36% <0.00%> (-40.91%)	⬇️
...emetry.Api/Internal/OpenTelemetryApiEventSource.cs	76.47% <0.00%> (-5.89%)	⬇️
...metryProtocol/Implementation/ActivityExtensions.cs	91.20% <0.00%> (-3.30%)	⬇️
...nTelemetry/Internal/OpenTelemetrySdkEventSource.cs	73.72% <0.00%> (-0.85%)	⬇️
...Telemetry/Internal/SelfDiagnosticsEventListener.cs	97.65% <0.00%> (+0.78%)	⬆️

[cijothomas]

Removed Redis tests (intergration) from main branch requirements. Good to merge.