Simplify column headers (#27557)

app/javascript/mastodon/components/__tests__/button-test.jsx

@@ -1,6 +1,7 @@
-import { render, fireEvent, screen } from '@testing-library/react';
 import renderer from 'react-test-renderer';
 
+import { render, fireEvent, screen } from 'mastodon/test_helpers';
+
 import { Button } from '../button';
 
 describe('<Button />', () => {