Fix a bug in the recursive rmdir

A directory containing a directory containing files where never deleted.

Example:

Let's consider this configuration:

```
/tmp/root
└── intermediate
	├── file1
	├── file2
    └── file3
```

This configuration was able to occured during a plugin update.

If NC was running a `rmdirr("/tmp/root");` (which seems to be done during a cron, but, that's not important), it would never deleted anything.

Indeed, the `$files` variable would contians only the `intermediate` directory.

Thus, during the loop to delete the content of the `/tmp/root` content, when `$fileInfo` will contains the descriptor of `/tmp/root/intermediate`, the `rmdir` PHP function would fails because this directory is not empty.... And maked the final `rmdir` (in the `$deleteSelf` condition).

Tested on `PHP 8.1.20 (built: Jun 15 2023 01:23:25) (NTS)`, the PHP version of the docker container provided by NC-AIO.

Signed-off-by: Ajabep <[email protected]>

lib/private/legacy/OC_Helper.php

@@ -173,7 +173,7 @@ public static function rmdirr($dir, $deleteSelf = true) {
 				if ($fileInfo->isLink()) {
 					unlink($fileInfo->getPathname());
 				} elseif ($fileInfo->isDir()) {
-					rmdir($fileInfo->getRealPath());
+					self::rmdirr($fileInfo->getRealPath());
 				} else {
 					unlink($fileInfo->getRealPath());
 				}