AP_NavEKF3: added in a check for high velocity innovation

if using GPS and our horizontal velocity innovation is high then mark
the filter as unhealthy, which causes an arming failure

this helps with ArduPilot#29384

Author: tridge

libraries/AP_NavEKF3/AP_NavEKF3_Outputs.cpp

@@ -28,6 +28,14 @@ bool NavEKF3_core::healthy(void) const
         return false;
     }
 
+    const float max_vel_innovation = 2.0;
+    if (onGround && PV_AidingMode == AID_ABSOLUTE &&
+        frontend->sources.useVelXYSource(AP_NavEKF_Source::SourceXY::GPS) &&
+        (sq(innovVelPos[0])+sq(innovVelPos[1])) > sq(max_vel_innovation)) {
+        // more than 2 m/s horizontal velocity innovation on the ground
+        return false;
+    }
+
     // all OK
     return true;
 }