AutoLineSmoothVel: don't use _velocity_setpoint for constraints

Unfortunately the constraints cannot be implemented using the
_constraints because the controller uses that directly. This
causes discontinuities in the velocity and/or accel at various
points of the flight. In particular this was used in Takeoff.

Instead this was done by changing target accel/velocity in the
jerk-optimal velocity planner for Z.

src/lib/flight_tasks/tasks/AutoMapper/FlightTaskAutoMapper.cpp

@@ -142,9 +142,7 @@ void FlightTaskAutoMapper::_prepareTakeoffSetpoints()
 {
 	// Takeoff is completely defined by target position
 	_position_setpoint = _target;
-	const float speed_tko = (_dist_to_ground > _param_mpc_land_alt1.get()) ? _constraints.speed_up :
-				_param_mpc_tko_speed.get();
-	_velocity_setpoint = Vector3f(NAN, NAN, -speed_tko); // Limit the maximum vertical speed
+	_velocity_setpoint = Vector3f(NAN, NAN, NAN);
 
 	_gear.landing_gear = landing_gear_s::GEAR_DOWN;
 }

src/lib/flight_tasks/tasks/AutoMapper/FlightTaskAutoMapper.hpp

@@ -70,7 +70,9 @@ protected:
 					_param_mpc_land_alt1, // altitude at which speed limit downwards reaches maximum speed
 					(ParamFloat<px4::params::MPC_LAND_ALT2>)
 					_param_mpc_land_alt2, // altitude at which speed limit downwards reached minimum speed
-					(ParamFloat<px4::params::MPC_TKO_SPEED>) _param_mpc_tko_speed
+					(ParamFloat<px4::params::MPC_TKO_SPEED>) _param_mpc_tko_speed,
+					(ParamFloat<px4::params::MPC_TKO_RAMP_T>)
+					_param_mpc_tko_ramp_t // time constant for smooth takeoff ramp
 				       );
 
 private: