Don't accept gestures by ForwardingGestureRecognizer (#7558)

ForwardingGestureRecognizer was previously accepting the gesture when the touch sequence ended, this was causing some other gesture recognizers to not accept the gestures (e.g tapping on the my location button in a Google Map didn't work).

shell/platform/darwin/ios/framework/Source/FlutterPlatformViews.mm

@@ -416,7 +416,7 @@ void FlutterPlatformViewsController::EnsureGLOverlayInitialized(
 
 - (void)touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event {
   [_flutterView touchesEnded:touches withEvent:event];
-  self.state = UIGestureRecognizerStateEnded;
+  self.state = UIGestureRecognizerStateFailed;
 }
 
 - (void)touchesCancelled:(NSSet*)touches withEvent:(UIEvent*)event {