move vehicle at rest detection ekf2 -> land_detector

- move vehicle at reset detection ekf2 -> land_detector
 - ekf_unit: reduce init period
   - Fake fusion is when at rest is quite strong and makes the variance reduce rapidly. Reduce the amount of time we wait before checking if the variances are still large enough.
 - ekf_unit: reduce minimum vel/pos variance required after init
   - Fake pos fusion has a low observation noise, making the vel/pos variances reduce quickly.

Co-authored-by:: bresch <brescianimathieu@gmail.com>

src/modules/land_detector/MulticopterLandDetector.cpp

@@ -285,11 +285,10 @@ bool MulticopterLandDetector::_get_maybe_landed_state()
 	}
 
 	// Next look if all rotation angles are not moving.
-	vehicle_angular_velocity_s vehicle_angular_velocity{};
-	_vehicle_angular_velocity_sub.copy(&vehicle_angular_velocity);
-	const Vector2f angular_velocity{vehicle_angular_velocity.xyz[0], vehicle_angular_velocity.xyz[1]};
 	const float max_rotation_scaled = math::radians(_param_lndmc_rot_max.get()) * landThresholdFactor;
 
+	matrix::Vector2f angular_velocity{_angular_velocity(0), _angular_velocity(1)};
+
 	if (angular_velocity.norm() > max_rotation_scaled) {
 		return false;
 	}