MulticopterLandDetector: Make land detection time configurable

The tree stages used arbitrary 350, 250 300ms totally 900ms
So this changes it to each stage to a third of the parameter.
Default it is 1 second -> 333ms per stage.

src/modules/land_detector/AirshipLandDetector.h

@@ -55,7 +55,6 @@ protected:
 	bool _get_ground_contact_state() override;
 	bool _get_landed_state() override;
 	void _set_hysteresis_factor(const int factor) override {};
-
 };
 
 } // namespace land_detector