Remove source map generation from webpack automock-loader

code/core/src/core-server/presets/webpack/loaders/webpack-automock-loader.ts

@@ -29,12 +29,11 @@ export default function webpackAutomockLoader(
 ) {
   // Retrieve the options passed in the resource query string (e.g., `?spy=true`).
   const options = this.getOptions();
-  const callback = this.async();
   const isSpy = options.spy === 'true';
 
   // Generate the mocked source code using the utility from @vitest/mocker.
   const mocked = getAutomockCode(source, isSpy, babelParser as any);
 
   // Return the transformed code to Webpack for further processing.
-  callback(null, mocked.toString(), mocked.generateMap());
+  return mocked.toString();
 }