popupMenu: Remove can_focus=True from Switch

Since this is a bin and not a button, and it doesn't have any click/keyboard
handling on its own (as in that case it needs a parent button wired like in
the messages list controls), it is confusing that it has can_focus set to
True. To avoid any confusion, this commit removes it without breaking anything
since it had no real use.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1920>

js/ui/popupMenu.js

@@ -324,7 +324,6 @@ var Switch = GObject.registerClass({
         super._init({
             style_class: 'toggle-switch',
             accessible_role: Atk.Role.CHECK_BOX,
-            can_focus: true,
             state,
         });
     }