move min/max distance to ground limits to FlightTask ManualAltitude

src/modules/flight_mode_manager/tasks/FlightTask/FlightTask.hpp

@@ -227,9 +227,6 @@ protected:
 	float _dist_to_bottom{}; /**< current height above ground level */
 	float _dist_to_ground{}; /**< equals _dist_to_bottom if valid, height above home otherwise */
 
-	float _min_distance_to_ground{-INFINITY}; /**< min distance to ground constraint */
-	float _max_distance_to_ground{INFINITY};  /**< max distance to ground constraint */
-
 	/**
 	 * Setpoints which the position controller has to execute.
 	 * Setpoints that are set to NAN are not controlled. Not all setpoints can be set at the same time.

src/modules/flight_mode_manager/tasks/ManualAltitude/FlightTaskManualAltitude.hpp

@@ -139,6 +139,9 @@ private:
 	bool _terrain_follow{false}; /**< true when the vehicle is following the terrain height */
 	bool _terrain_hold{false}; /**< true when vehicle is controlling height above a static ground position */
 
+	float _min_distance_to_ground{-INFINITY}; /**< min distance to ground constraint */
+	float _max_distance_to_ground{INFINITY};  /**< max distance to ground constraint */
+
 	/**
 	 * Distance to ground during terrain following.
 	 * If user does not demand velocity change in D-direction and the vehcile