disable side slip fusion for tailsitters

The attitude frame is wrong for tailsitters doing side slip fusion for wind estimation.
It doesn't take into account that the frames is 90deg tilted in FW flight.

Signed-off-by: Silvan Fuhrer <silvan@auterion.com>

src/modules/ekf2/EKF2.cpp

@@ -2360,6 +2360,12 @@ void EKF2::UpdateSystemFlagsSample(ekf2_timestamps_s &ekf2_timestamps)
 
 			// let the EKF know if the vehicle motion is that of a fixed wing (forward flight only relative to wind)
 			flags.is_fixed_wing = (vehicle_status.vehicle_type == vehicle_status_s::VEHICLE_TYPE_FIXED_WING);
+
+			if (vehicle_status.is_vtol_tailsitter && _params->beta_fusion_enabled) {
+				PX4_WARN("Disable EKF beta fusion as unsupported for tailsitter");
+				_param_ekf2_fuse_beta.set(0);
+				_param_ekf2_fuse_beta.commit_no_notification();
+			}
 		}
 
 		// vehicle_land_detected

src/modules/ekf2/ekf2_params.c

@@ -1073,6 +1073,7 @@ PARAM_DEFINE_FLOAT(EKF2_EV_POS_Z, 0.0f);
 * value will determine the minimum airspeed which will still be fused. Set to about 90% of the vehicles stall speed.
 * Both airspeed fusion and sideslip fusion must be active for the EKF to continue navigating after loss of GPS.
 * Use EKF2_FUSE_BETA to activate sideslip fusion.
+* Note: side slip fusion is currently not supported for tailsitters.
 *
 * @group EKF2
 * @min 0.0