Revert "Fix i18n domain"

This reverts commit 8aebe3f5. The fix for bug [#480424](https://bugs.kde.org/show_bug.cgi?id=480424) was later fixed in [Plasma Workspace](plasma-workspace@2eab616a), and dealt with it. This one broke existing translations. Needs to be cherry-picked into 6.0 (sorry about that).

(cherry picked from commit 84900edc)