manual_yaw: compensate for yaw estimate convergence

When the yaw estimate is converging, the controller makes the drone yaw
in order to follow the current setpoint. This is unintuitive for the
pilot and it is preferable if the drone continues to fly towards the
same physical direction.

src/modules/simulation/simulator_sih/sih.cpp

@@ -546,6 +546,7 @@ void Sih::publish_ground_truth(const hrt_abstime &time_now_us)
 
 		local_position.heading = Eulerf(_q).psi();
 		local_position.heading_good_for_control = true;
+		local_position.unaided_heading = NAN;
 
 		local_position.timestamp = hrt_absolute_time();
 		_local_position_ground_truth_pub.publish(local_position);