Migrate from Jest to Vitest (#34454)

eslint.config.mjs

@@ -247,6 +247,7 @@ export default tseslint.config([
             'config/webpack/**',
             'app/javascript/mastodon/performance.js',
             'app/javascript/mastodon/test_setup.js',
+            'app/javascript/mastodon/test_helpers.tsx',
             'app/javascript/**/__tests__/**',
           ],
         },
@@ -387,9 +388,7 @@ export default tseslint.config([
     files: ['**/__tests__/*.js', '**/__tests__/*.jsx'],
 
     languageOptions: {
-      globals: {
-        ...globals.jest,
-      },
+      globals: globals.vitest,
     },
   },
 ]);