message: camera: reduce message requests
  Let's reduce the load on the autopilot a bit by reducing the amount of
  requests for commands that we do.
diff: @@ -499,9 +499,13 @@ void CameraImpl::subscribe_information(const Camera::InformationCallback& callba
  }
  if (callback) {
  - _parent->add_call_every([this]() { request_status(); }, 1.0, &_status.call_every_cookie);
  + if (_status.call_every_cookie == nullptr) {
  + _parent->add_call_every(
  + [this]() { request_status(); }, 5.0, &_status.call_every_cookie);
  + }
  } else {
  _parent->remove_call_every(_status.call_every_cookie);
  + _status.call_every_cookie = nullptr;
  }
  }
  @@ -702,7 +706,7 @@ void CameraImpl::subscribe_mode(const Camera::ModeCallback callback)
  if (callback) {
  _parent->add_call_every(
  - [this]() { request_camera_settings(); }, 1.0, &_mode.call_every_cookie);
  + [this]() { request_camera_settings(); }, 5.0, &_mode.call_every_cookie);
  } else {
  _parent->remove_call_every(_mode.call_every_cookie);
  }
  @@ -732,9 +736,13 @@ void CameraImpl::subscribe_status(const Camera::StatusCallback callback)
  _status.subscription_callback = callback;
  if (callback) {
  - _parent->add_call_every([this]() { request_status(); }, 1.0, &_status.call_every_cookie);
  + if (_status.call_every_cookie == nullptr) {
  + _parent->add_call_every(
  + [this]() { request_status(); }, 5.0, &_status.call_every_cookie);
  + }
  } else {
  _parent->remove_call_every(_status.call_every_cookie);
  + _status.call_every_cookie = nullptr;
  }
  }
  