examples: remove `with-emotion-*` directories (#73674)
### What?
Delete
[`with-emotion-swc`](https://github.com/vercel/next.js/tree/canary/examples/with-emotion-swc)
and
[`with-emotion-vanilla`](https://github.com/vercel/next.js/tree/canary/examples/with-emotion-vanilla)
examples.
### Why?
At #62771, consolidated all emotion examples into a single one.
These are no longer worth keeping.
### Adding or Updating Examples
- [x] The "examples guidelines" are followed from our contributing doc
https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md
- [x] Make sure the linting passes by running `pnpm build && pnpm lint`.
See
https://github.com/vercel/next.js/blob/canary/contributing/repository/linting.md
CC: @samcx
Co-authored-by: Sam Ko <sam@vercel.com>
