[php-src] Issue #20762: ext/soap/tests/soap_qname_crash.phpt requires more than 2GB of memory

Issue: https://github.com/php/php-src/issues/20762
Author: nwellnhof

### Description

`ext/soap/tests/soap_qname_crash.phpt` requires more than 2GB of memory and fails with OOM errors on smaller virtual machines. Removing the test case makes the test suite pass on `codeberg-tiny`, for example.

Another issue is that there are plans to fix string handling in libxml2. At some point, support for strings larger than 2GB might be implemented which would change the test output.

### PHP Version

```plain
PHP 8.6.0-dev (cli) (built: Dec 22 2025 16:23:45) (NTS DEBUG)
Copyright (c) The PHP Group
Zend Engine v4.6.0-dev, Copyright (c) Zend Technologies
    with Zend OPcache v8.6.0-dev, Copyright (c), by Zend Technologies
```

### Operating System

_No response_