fix: file names stay ASCII as on TYPO3 10 (UTF8filesystem off)

The fresh TYPO3 13 installation got UTF8filesystem = true from the core's
factory configuration; TYPO3 10 ran with the default false, so uploads
turned umlauts into ASCII (Bärenhütte.jpg -> Baerenhuette.jpg) and no file
in sys_file has a non-ASCII name. With true and no UTF-8 system locale,
escapeshellarg() drops those characters and image processing misses the
file (environment check warning). Back to false: the TYPO3 10 behaviour,
no locale needed, and file URLs and CDN paths stay free of encoded umlauts.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

config/system/settings.php

@@ -178,7 +178,7 @@ return [
         'transport_smtp_username' => '',
     ],
     'SYS' => [
-        'UTF8filesystem' => true,
+        'UTF8filesystem' => false,
         'caching' => [
             'cacheConfigurations' => [
                 'hash' => [