message: core: retry longer to get autopilot version msg
  This should resolve an error where we give up to early and therefore
  never receive a autopilot version message and therefore we don't know
  whether we can use the mission int mode.
diff: @@ -189,7 +189,7 @@ void SystemImpl::process_heartbeat(const mavlink_message_t &message)
  if (is_autopilot(message.compid) && !have_uuid()) {
  request_autopilot_version();
  - } else if (!is_autopilot(message.compid) && !have_uuid() && ++_non_autopilot_heartbeats >= 2) {
  + } else if (!is_autopilot(message.compid) && !have_uuid() && ++_non_autopilot_heartbeats >= 10) {
  // We've received consecutive heartbeats (atleast twice) from a
  // non-autopilot system! Lets not delay for filling UUID anymore.
  _uuid = message.sysid;
  