fix: ignore error when removing "is writable" test file

Signed-off-by: Robin Appelman <[email protected]>

lib/private/legacy/OC_Util.php

@@ -453,7 +453,7 @@ public static function checkServer(\OC\SystemConfig $config) {
 					];
 				} else {
 					fclose($handle);
-					unlink($testFile);
+					@unlink($testFile);
 				}
 			} else {
 				$errors = array_merge($errors, self::checkDataDirectoryPermissions($CONFIG_DATADIRECTORY));