message: Add verbose error message for capture_tpu_profile
diff: @@ -156,7 +156,8 @@ bool NewSession(const string& service_addr,
  channel_args));
  NewProfileSessionResponse new_session_response;
  TF_QCHECK_OK(FromGrpcStatus(
  - stub->NewSession(&context, new_session_request, &new_session_response)));
  + stub->NewSession(&context, new_session_request, &new_session_response)))
  + << new_session_response.error_message();
  std::cout << "Profile session succeed for host(s):"
  << str_util::Join(hostnames, ",") << std::endl;
  