flight tasks: move weather vane yaw handler from Altitude to Position task

src/lib/FlightTasks/tasks/ManualAltitude/FlightTaskManualAltitude.cpp

@@ -284,12 +284,6 @@ void FlightTaskManualAltitude::_updateHeadingSetpoints()
 			}
 		}
 	}
-
-	// check if an external yaw handler is active and if yes, let it compute the yaw setpoints
-	if (_ext_yaw_handler != nullptr && _ext_yaw_handler->is_active()) {
-		_yaw_setpoint = NAN;
-		_yawspeed_setpoint += _ext_yaw_handler->get_weathervane_yawrate();
-	}
 }
 
 void FlightTaskManualAltitude::_updateSetpoints()