scripting: Terminate using meta_context_terminate()

With meta_exit() we bypass the tear down procedures, making the test
case excercising much less code paths. Use meta_context_terminate()
instead, as that exits the main loop and goes through proper shutdown.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1349>

js/ui/scripting.js

@@ -293,7 +293,7 @@ async function _runPerfScript(scriptModule, outputFile) {
         Meta.exit(Meta.ExitCode.ERROR);
     }
 
-    Meta.exit(Meta.ExitCode.SUCCESS);
+    global.context.terminate();
 }
 
 /**