[TF Data Service] Use the gRPC local pool rather than the default global pool. In edge cases, this change should improve the networking throughput on TPUs. In regular cases, this change should be a no op.

PiperOrigin-RevId: 357022295
Change-Id: I356f365488a0bb96d076029597c27ca72d4902b7

Author: Allen Wang

tensorflow/core/data/service/data_service.cc

@@ -233,6 +233,7 @@ Status DataServiceDispatcherClient::EnsureInitialized() {
       CredentialsFactory::CreateClientCredentials(protocol_, &credentials));
   grpc::ChannelArguments args;
   args.SetMaxReceiveMessageSize(std::numeric_limits<int32>::max());
+  args.SetInt(GRPC_ARG_USE_LOCAL_SUBCHANNEL_POOL, true);
   auto channel = grpc::CreateCustomChannel(address_, credentials, args);
   stub_ = DispatcherService::NewStub(channel);
   return Status::OK();