Fix deprecated readdir() without argument for PHP 8.5

Looks the only place to fix

This argument is nullable (and exists) since 8.0.0. So based on https://www.drupal.org/docs/getting-started/system-requirements/php-requ... → , I think this is good to merge. Existing test coverage should be enough, as @andypost proved this fails on php5. I don't think we have a way (yet) of proving this passes tho.

I'm assuming we want this backported to 11.2.x.

I checked that we don't need this specific fix for 10.5.x, but didn't check if there are any other readdir(), rewinddir(), and closedir() usages in that branch. I don't even know if supporting 10.5.x means we should ensure it works with php85

+1 RTBC here.

Committed and pushed 6c0071f6725 to 11.x and de03f6e2853 to 11.2.x. Thanks!

andypost → closed merge request !12952

thank you!