Trace export to opentelemetry otlp/grpc endpoint

[seankhliao]

Feature request

I'd like to configure Tekton to export its traces natively via the OTLP/gRPC protocol instead of jaeger http thrift. Even jaeger itself now natively supports OTLP: announcement blog post

Use case

While an opentelemetry collector (which supports jaeger thrift) may be the most likely export target for most people using OTLP, it is nevertheless much nicer to only need to think about and manage a single protocol / receiver for ingesting traces, plus the (hand-waving) less overhead from protocol conversions.

Additional Considerations

Is it necessary to support both OTLP/HTTP and OTLP/gRPC? Some SaaS platforms only support the HTTP variant.

What's the additional API exposed to the end user for this (#7001)? Presumably "just" a protocol key in the tracing configmap and reusing the endpoint key?

If I understood the implementation correctly, it should be sufficient to expose/parse the config in pkg/apis/config/tracing.go and switch the exporter in pkg/tracing/tracing.go ?