ekf2: use yaw emergency estimator more aggressively

During the whole flight, if the difference between the yaw estimate from
EKF2 and the emergency estimator is large and that the GNSS velocity
fusion is failing continuously, immediately reset to the emergency yaw
estimate.

src/modules/ekf2/EKF/control.cpp

@@ -612,10 +612,3 @@ void Ekf::controlAuxVelFusion()
 		}
 	}
 }
-
-bool Ekf::hasHorizontalAidingTimedOut() const
-{
-	return isTimedOut(_time_last_hor_pos_fuse, _params.reset_timeout_max)
-	       && isTimedOut(_time_last_hor_vel_fuse, _params.reset_timeout_max)
-	       && isTimedOut(_aid_src_optical_flow.time_last_fuse, _params.reset_timeout_max);
-}