chore(storybook): remove core-js plugin from storybook config

ref: storybookjs/storybook#7445

Author: emyarod

Diff for: packages/react/.storybook/webpack.config.js

@@ -138,5 +138,9 @@ module.exports = ({ config, mode }) => {
     plugins: [new FeatureFlagProxyPlugin()],
   };
 
+  config.plugins = config.plugins.filter(
+    p => String(p.resourceRegExp) !== '/core-js/'
+  );
+
   return config;
 };