ci: use Webpack 4 in `webpack_react` and `sfcVue` E2E tests
ci: use Webpack 4 in `webpack_react` and `sfcVue` E2E tests

Webpack 5 is officially out for a few days but it looks like Storybook is not 100% compatible with it yet.

storybooks/react-storybook,storybooks/storybook,storybooks/react-storybook,storybooks/react-storybook,storybooks/storybook,storybooks/storybook,storybooks/storybook,kadirahq/react-storybook,storybooks/react-storybook,storybooks/storybook,storybooks/storybook,storybooks/storybook,kadirahq/react-storybook