message: client: add timeout to submit_transaction
  Closes:
  Approved by: opsguy
diff: @@ -67,7 +67,14 @@ impl AdmissionControlClientBlocking {
  request: SubmitTransactionRequest,
  ) -> Result<SubmitTransactionResponse, tonic::Status> {
  let (rt, client) = self.client()?;
  - rt.block_on(client.submit_transaction(request))
  + rt.block_on(async {
  + tokio::time::timeout(
  + std::time::Duration::from_millis(5000),
  + client.submit_transaction(request),
  + )
  + .await
  + })
  + .map_err(|_| tonic::Status::new(tonic::Code::DeadlineExceeded, ""))?
  .map(tonic::Response::into_inner)
  }
  