[Proposal]: Deprecate grpc-plugin (sidecar) support

[yurishkuro]

Requirement

As maintainers we want to minimize the amount of code and niche use cases we must support.

Problem

Storage plugins were originally implemented via hashicorp/grpc-plugin library, which requires running a sidecar process implementing the plugin. Since this process communicates with the main binary via gRPC API, we later realized that we could also support a Remote Storage API implemented by independent gRPC servers, which is generally a more flexible model than running a sidecar, while the sidecar mode is still possible via special deployment, e.g. in k8s. So now we support two variants of storage plugins, which is both confusing to the users and doubles the amount of code to support.

Proposal

Deprecate the use of sidecar plugin model, and only support remote storage API via gRPC.

cc @jaegertracing/jaeger-maintainers

Open questions

No response

[yurishkuro]

duplicate of #4647