js: Always use AppSystem to lookup apps

There is no good reason for bypassing the application cache in
AppSystem and loading .desktop files again.

https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1093

js/ui/appDisplay.js

@@ -1251,8 +1251,8 @@ var AppSearchProvider = class AppSearchProvider {
         let results = [];
         groups.forEach(group => {
             group = group.filter(appID => {
-                let app = Gio.DesktopAppInfo.new(appID);
-                return app && app.should_show();
+                const app = this._appSys.lookup_app(appID);
+                return app && app.app_info.should_show();
             });
             results = results.concat(group.sort(
                 (a, b) => usage.compare(a, b)