cleanup: Remove left-over imports

Unfortunately this slipped through our CI tests, as the script
filters errors by lines that are modified by the corresponding
merge request.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/710

js/ui/pointerA11yTimeout.js

@@ -1,5 +1,5 @@
 /* exported PointerA11yTimeout */
-const { Clutter, GLib, GObject, Meta, St } = imports.gi;
+const { Clutter, GObject, Meta, St } = imports.gi;
 const Main = imports.ui.main;
 const Cairo = imports.cairo;