st-container: Remove st_container_destroy_children

It was a simple wrapper around clutter_actor_destroy_all_children.

https://bugzilla.gnome.org/show_bug.cgi?id=670034

js/ui/shellMountOperation.js

@@ -359,7 +359,7 @@ const ShellProcessesDialog = new Lang.Class({
 
     _setAppsForPids: function(pids) {
         // remove all the items
-        this._applicationList.destroy_children();
+        this._applicationList.destroy_all_children();
 
         pids.forEach(Lang.bind(this, function(pid) {
             let tracker = Shell.WindowTracker.get_default();