layout: Remove some outdated set_hidden_from_pick calls

XDND no longer uses CLUTTER_PICK_ALL, so we don't need to hide
certain actors from pick anymore.

js/ui/layout.js

@@ -227,11 +227,6 @@ const LayoutManager = new Lang.Class({
         this._backgroundGroup.lower_bottom();
         this._bgManagers = [];
 
-        // This blocks the XDND picks from finding the activities button
-        // and we never attempt to pick anything from it anyway so make
-        // it invisible from picks
-        Shell.util_set_hidden_from_pick(global.top_window_group, true);
-
         // Need to update struts on new workspaces when they are added
         global.screen.connect('notify::n-workspaces',
                               Lang.bind(this, this._queueUpdateRegions));