nixos/doc/rl-2505: Fix wording of `users.users` subuid allocation note (#408018)

  to review the new defaults and description of

  [](#opt-services.nextcloud.poolSettings).

- In `users.users` allocation on systems with multiple users it could happen that collided with others. Now these users get new subuid ranges assigned. When this happens, a warning is issued on the first activation. If the subuids were used (e.g. with rootless container managers like podman), please change the ownership of affected files accordingly.

- In `users.users` subuid allocation on systems with multiple users it could happen that some users' allocated subuid ranges collided with others. Now these users get new subuid ranges assigned. When this happens, a warning is issued on the first activation. If the subuids were used (e.g. with rootless container managers like podman), please change the ownership of affected files accordingly.

- The `services.locate` module does no longer support findutil's `locate` due to its inferior performance compared to `mlocate` and `plocate`. The new default is `plocate`.

  As the `service.locate.localuser` option only applied when using findutil's `locate`, it has also been removed.