Remove the special server type DM_ENV_RPC and use instead a vanilla GRPC server.
Remove the special server type DM_ENV_RPC and use instead a vanilla GRPC server.

PiperOrigin-RevId: 321326405
Change-Id: I092e51a7b78290e44e61a81df9630c7334e7f7b9

deepmind/dm_memorytasks