docs: remove deprecated url.parse() from custom server example (#86986)
This PR updates the custom server documentation to remove usage of
Node's
deprecated `url.parse()` API. The example does not require URL parsing,
since
the `parsedUrl` argument is optional for the Next.js `RequestHandler`.
Removing `url.parse()` avoids Node deprecation warnings (DEP0116,
DEP0169) and
keeps the example aligned with current best practices.
### What changed?
- Removed the `url.parse()` import and usage.
- Removed unused `parsedUrl` variable.
- Updated both TS and JS examples to use `handle(req, res)` directly.
### Why?
- `url.parse()` is deprecated in modern Node versions.
- The example works without URL parsing.
- Simplifies the docs and matches recommended APIs.
Fixes #86951 and https://github.com/vercel/next.js/issues/83183
Co-authored-by: Joseph <joseph.chamochumbi@vercel.com>