Change danish language code from "da_DK" to "da"

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Label this issue
• Close this issue

I would prefer if the language code for the danish translation is changed from "da_DK" to "da".

Folder name and the header in the po file: https://gitlab.com/gitlab-org/gitlab/-/blob/master/locale/da_DK/

Crowdin website is using "da" so that's fine: https://translate.gitlab.com/project/gitlab-ee/da