tetra: remove the stacktrace-tree command and gRPC API

[mtardy]

The stacktrace-tree is the legacy stuff that was used to print stack trace with tetragon, it's been replaced by this modern way of doing via TracingPolicy and events https://tetragon.io/docs/concepts/tracing-policy/selectors/#stack-traces. Let's remove all that old stuff, it's been dead forever.

[FedeDP]

Ehy Mahé! Is this something we want cleaned up now or do we want to introduce a deprecation notice + period?

[mtardy]

Ehy Mahé! Is this something we want cleaned up now or do we want to introduce a deprecation notice + period?

I don't think we really care about doing the whole deprecation thing as it is just plugged into nothing for now

tetragon/pkg/server/server.go

Lines 314 to 319 in c7812db

	func (s *Server) GetStackTraceTree(_ context.Context, req *tetragon.GetStackTraceTreeRequest) (*tetragon.GetStackTraceTreeResponse, error) {
	logger.GetLogger().Debug("Received a GetStackTraceTree request", "request", req)
	err := errors.New("unsupported GetStackTraceTree")
	logger.GetLogger().Warn("Server GetStackTraceTree failed", logfields.Error, err)
	return nil, err
	}