Rename translation domains to match the KCM plugin name
For QML KCMs, KF6 expects plugin name and translation domain name to match (based on a comment by @nicolasfella). Let's adapt the latter now to keep QML port MRs tidy.
This commit does not include renaming the actual .po files, because git audit hooks prevent those renames from being pushed.
@teams/localization, can you advise how to do this properly? I don't have much insight into the translation infrastructure and it would appear that without corresponding .po file renames, this commit/MR is incomplete.