[cna] upgrade templates tailwind to v4 (#75407)
Since Tailwind v4 was released, update the create-next-app templates.
This PR made change of following process:
1. Remove tailwind config.
2. Update the `globals.css` file.
3. Add `--geist-` font CSS variable to the `globals.css` file.
4. Change `postcss` dependency to `@tailwindcss/postcss`.
5. Update postcss config.
6. Update tests.
**Note:** Removed the types for postcss added at
https://github.com/vercel/next.js/pull/63380 since it requires
additional
[postcss-load-config](https://www.npmjs.com/package/postcss-load-config)
dependency.
