Remove unneeded parts in mount_search_settings_spec

- We can simply wait for the method (no need for wait_for_promises)
- `mockReset` isn't needed due to jest config

spec/frontend/pages/projects/edit/mount_search_settings_spec.js

-import waitForPromises from 'helpers/wait_for_promises';
 import { setHTMLFixture, resetHTMLFixture } from 'helpers/fixtures';
 import initSearch from '~/search_settings';
 import mountSearchSettings from '~/pages/projects/edit/mount_search_settings';
@@ -7,24 +6,19 @@ jest.mock('~/search_settings');
 
 describe('pages/projects/edit/mount_search_settings', () => {
   afterEach(() => {
-    initSearch.mockReset();
     resetHTMLFixture();
   });
 
   it('initializes search settings when js-search-settings-app is available', async () => {
     setHTMLFixture('<div class="js-search-settings-app"></div>');
 
-    mountSearchSettings();
-
-    await waitForPromises();
+    await mountSearchSettings();
 
     expect(initSearch).toHaveBeenCalled();
   });
 
   it('does not initialize search settings when js-search-settings-app is unavailable', async () => {
-    mountSearchSettings();
-
-    await waitForPromises();
+    await mountSearchSettings();
 
     expect(initSearch).not.toHaveBeenCalled();
   });