This commit revisits the recently updated `PORT_PATTERN` in
`UriComponentsBuilder`. The fix introduced in gh-26905 fails with
ambiguous URL patterns, especially when the port and path parts of the
pattern are hard to differentiate, for example
"https://localhost:{port}{path}".
This commit reinstates the previous behavior without undoing the actual
fix. The only limitation introduced here is the fact that only a single
pattern variable is allowed for the port pattern part.
Fixes gh-27039
e35fe33b72