`ignored_key_prefixes` not respected when deleting files

[MartijnCuppens]

This line: https://github.com/translation/laravel/blob/f4e63b9b4af039022344b2d284d8b43c413826dc/src/TranslationSaver.php#L41

will delete all files in the language directory, ignoring the keys set in ignored_key_prefixes.

Some logic should be implemented to not delete the files that are ignored.