Fixed profile notifications not being editable

Closes #44198

app/assets/javascripts/pages/profiles/notifications/show/index.js

+import NotificationsForm from '../../../../notifications_form';
+import notificationsDropdown from '../../../../notifications_dropdown';
+
+document.addEventListener('DOMContentLoaded', () => {
+  new NotificationsForm(); // eslint-disable-line no-new
+  notificationsDropdown();
+});

spec/features/profiles/user_visits_notifications_tab_spec.rb

@@ -16,6 +16,6 @@ feature 'User visits the notifications tab', :js do
     first('#notifications-button').click
     click_link('On mention')
-    expect(page).to have_content('On mention')
+    expect(page).to have_selector('#notifications-button', text: 'On mention')
   end
 end