TL;DR: Don't worry, it's good! :)
You've been translating very quickly and this language has passed the threshold of 13% of translated messages (see Translating:MediaWiki). It is now officially exported from translatewiki to the MediaWiki source code repository. Therefore, it no longer needs to be listed separately in translatewiki's local LanguageSettings.php file, and it takes the configuration from the global language configuration file in core MediaWiki.