[php-src] Issue #22138: libxml and XMLReader tests fail with "Can't resolve URI" errors because external entity loading is disabled by default

Issue: https://github.com/php/php-src/issues/22138
Author: RimacC2-EV

### Description

The following code:

(missing because the issue occurred when making php from source)

Resulted in this output:

[php_test_results_20260524_0210.txt](https://github.com/user-attachments/files/28186278/php_test_results_20260524_0210.txt)

But I expected this output instead:

(successful making)

(The title is generated with AI due to the lack of the skills of reading and analyzing the error report file)
(Not an native English speaker, if there's anything unclear, please notify me, thanks!)


### PHP Version

```plain
PHP 8.5.6 (cli) (built: May 24 2026 10:08:46) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.5.6, Copyright (c) Zend Technologies
    with Zend OPcache v8.5.6, Copyright (c), by Zend Technologies
```

### Operating System

Arch Linux(CachyOS)