Run CI against freethreading python builds

[emdneto]

Originally posted by @aabmass in #4798 (comment)

[emdneto]

For packages that depend on grpcio we need to wait for grpc/grpc#38762

[emdneto]

Update those tests when the issue with grpcio is fixed

• test-opentelemetry-getting-started
• test-opentelemetry-exporter-otlp-combined
• test-opentelemetry-exporter-otlp-proto-grpc-{oldest,latest}

[tammy-baylis-swi]

OpenTelemetry Specification 1.58.0 has introduced deprecation of OpenCensus compatibility, so I have edited the above list to exclude test-opentelemetry-exporter-opencensus and test-opentelemetry-opencensus-shim.