https://github.com/zed-extensions/php/blob/9a119b18eeb247072964a19ce46fab54bbd1bb30/extension.toml
provides 3 language servers for `php`, so `...` will always include all
3 if those are not excluded or included explicitly.

Change the configs and docs so, that only one php language server is
used.

Release Notes:

- N/A