[php-src] Issue #22289: opcache, file caching: About problems with multiple pools/users

Issue: https://github.com/php/php-src/issues/22289
Author: neufeind

### Description

It can happen that files in the file_cache collide. If they come from separate pools with separate users it can happen that one pool/user added a file and it can't be opened/overwritten by the other.
Can this be avoided by using the full file-path in the cache, maybe placeholders for the poolname or so? If those are separate pools then separate owners would not cause a collision.

### PHP Version

```plain
PHP 8.5.7 (cli) (built: Jun  2 2026 20:59:56) (NTS gcc x86_64)
Copyright (c) The PHP Group
Built by Remi's RPM repository <https://rpms.remirepo.net/> #StandWithUkraine
Zend Engine v4.5.7, Copyright (c) Zend Technologies
    with Zend OPcache v8.5.7, Copyright (c), by Zend Technologies
```

### Operating System

RHEL 9