Protobuf Services should be resolved by their full name

I noticed this while investigating test failures resulting from HBASE-26542. The test in question (TestRpcServerSlowConnectionSetup) builds a connection header by populating the serviceName field with the service descriptor's getFullName() method. The value returned by getFullName() is the protobuf service's package and name. However, down in RpcServer, we resolve the service named by the connection header using the service descriptor's getName() method. getName() returns the protobuf service's name, without the package.

It is my opinion that this is a bug in the RpcServer, it should resolve services using their fully qualified name.