[Instrumentation.SqlClient] Stop emitting db.statement_type attribute

[Kielek]

Fixes #
Design discussion issue #

Changes

[Instrumentation.SqlClient] Stop emitting db.statement_type attribute.
It was introduced in https://github.com/open-telemetry/opentelemetry-dotnet/pull/761/files#r450626620. It is not part of semantic convention. I didn't find any other occurrence for this except open-telemetry/opentelemetry-dotnet-contrib#1559

As a separate work, we should consider adding db.operation/sanitizing db.statement.

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) N/A

[codecov]

Codecov Report

Attention: 21 lines in your changes are missing coverage. Please review.

Comparison is base (6250307) 83.38% compared to head (fbf5ccf) 83.06%.
Report is 57 commits behind head on main.

❗ Current head fbf5ccf differs from pull request most recent head 1fb9863. Consider uploading reports for the commit 1fb9863 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5301      +/-   ##
==========================================
- Coverage   83.38%   83.06%   -0.32%     
==========================================
  Files         297      272      -25     
  Lines       12531    11971     -560     
==========================================
- Hits        10449     9944     -505     
+ Misses       2082     2027      -55     

Flag	Coverage Δ
unittests	?
unittests-Instrumentation-Experimental	24.64% <47.22%> (?)
unittests-Instrumentation-Stable	24.64% <47.22%> (?)
unittests-Solution-Experimental	83.05% <77.41%> (?)
unittests-Solution-Stable	83.06% <77.41%> (?)

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

Files	Coverage Δ
....Api/Context/Propagation/TraceContextPropagator.cs	90.00% <100.00%> (+0.52%)	⬆️
...etryProtocol/Implementation/ExperimentalOptions.cs	100.00% <ø> (ø)
...tation/OpenTelemetryProtocolExporterEventSource.cs	100.00% <100.00%> (ø)
...rotocol/Implementation/OtlpLogRecordTransformer.cs	95.41% <100.00%> (+1.95%)	⬆️
...tation.AspNetCore/Implementation/HttpInListener.cs	89.79% <100.00%> (+0.21%)	⬆️
...AspNetCore/Implementation/HttpInMetricsListener.cs	89.74% <100.00%> (+0.26%)	⬆️
...ntation.GrpcNetClient/GrpcClientInstrumentation.cs	100.00% <100.00%> (ø)
...NetClient/GrpcClientTraceInstrumentationOptions.cs	100.00% <ø> (ø)
...ent/Implementation/GrpcClientDiagnosticListener.cs	75.80% <100.00%> (-2.77%)	⬇️
...n.GrpcNetClient/TracerProviderBuilderExtensions.cs	100.00% <100.00%> (ø)
... and 13 more

... and 32 files with indirect coverage changes