UX: move vertical admin plugin nav to horizontal overflow nav (#20319)

app/assets/javascripts/admin/addon/controllers/admin-plugins.js

@@ -1,4 +1,3 @@
-import { action } from "@ember/object";
 import Controller from "@ember/controller";
 import { inject as service } from "@ember/service";
 
@@ -24,14 +23,6 @@ export default Controller.extend({
       .filter(Boolean);
   },
 
-  @action
-  toggleMenu() {
-    const adminDetail = document.querySelector(".admin-detail");
-    ["mobile-closed", "mobile-open"].forEach((state) => {
-      adminDetail.classList.toggle(state);
-    });
-  },
-
   routeExists(routeName) {
     try {
       this.router.urlFor(routeName);