backgroundMenu: Drop grab-op-begin signal connection

This is done just to "reset" the click action when a grab operation
begins. With grab ops being based on ClutterGrab now, the action
will be implicitly reset when these happen. This is unnecessary now.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2526>

js/ui/backgroundMenu.js

@@ -56,9 +56,6 @@ function addBackgroundMenu(actor, layoutManager) {
     });
     actor.add_action(clickAction);
 
-    global.display.connectObject('grab-op-begin',
-        () => clickAction.release(), actor);
-
     actor.connect('destroy', () => {
         actor._backgroundMenu.destroy();
         actor._backgroundMenu = null;