http3: quiche+ngtcp2 improvements

- quiche: error transfers that try to receive on a closed
  or draining connection
- ngtcp2: use callback for extending max bidi streams. This
  allows more precise calculation of MAX_CONCURRENT as we
  only can start a new stream when the server acknowledges
  the close - not when we locally have closed it.
- remove a fprintf() from h2-download client to avoid excess
  log files on tests timing out.

Closes #13475

tests/http/clients/h2-download.c

@@ -380,7 +380,6 @@ int main(int argc, char *argv[])
     if(still_running) {
       /* wait for activity, timeout or "nothing" */
       mc = curl_multi_poll(multi_handle, NULL, 0, 1000, NULL);
-      fprintf(stderr, "curl_multi_poll() -> %d\n", mc);
     }
 
     if(mc)