FIX: Reset category edit page button state (#11218)

Fixes two small issues:
- buttons stayed disabled after deleting a category
- on a newly-created category, the Edit button was missing on the category landing page

app/assets/javascripts/discourse/app/controllers/edit-category-tabs.js

@@ -95,6 +95,7 @@ export default Controller.extend({
             model.setProperties({
               slug: result.category.slug,
               id: result.category.id,
+              can_edit: result.category.can_edit,
               permission: PermissionType.FULL,
               notification_level: NotificationLevels.REGULAR,
             });
@@ -115,15 +116,19 @@ export default Controller.extend({
         I18n.t("yes_value"),
         (result) => {
           if (result) {
-            this.model.destroy().then(
+            this.model
+              .destroy()
+              .then(
                 () => {
                   this.transitionToRoute("discovery.categories");
                 },
                 () => {
                   this.displayErrors([I18n.t("category.delete_error")]);
-                this.set("deleting", false);
                 }
-            );
+              )
+              .finally(() => {
+                this.set("deleting", false);
+              });
           } else {
             this.set("deleting", false);
           }