[php-src] Issue #20961: run-tests.phpt `-s` option is broken

Issue: https://github.com/php/php-src/issues/20961
Author: ndossche

### Description

Run:

```sh
./sapi/cli/php ./run-tests.php -s foobar ext/openssl/tests/gh13860.phpt
```

Notice how `foobar` is not created.
This is because of the following early return which is hit:

https://github.com/php/php-src/blob/146b535a6d33c5e34c29a347a2db7edb102d1e60/run-tests.php#L909-L911

because the _same_ code path that calls `save_results`:

https://github.com/php/php-src/blob/146b535a6d33c5e34c29a347a2db7edb102d1e60/run-tests.php#L704

But I have no idea why

### PHP Version

```plain
8.4+
```

### Operating System

_No response_