message: Add trace logging to remove_stream_manager
diff: @@ -925,6 +925,7 @@ bool scheduled_actor::add_stream_manager(stream_slots id,
  }
  bool scheduled_actor::remove_stream_manager(stream_slots id) {
  + CAF_LOG_TRACE(CAF_ARG(id));
  if (stream_managers_.erase(id) == 0)
  return false;
  if (stream_managers_.empty())
  