Adapt the KF release scripts to the new i18n structure

As the new flattened i18n structure is built around the unique
repository identifier, a lot of code can be simplified
as the translation file locations don't need to be guessed anymore.

Use $repoid for the unique repository identifier (i.e. kio)
and $repo for the full repository path (i.e. frameworks/kio)
but leave out the files whose only change would be the rename
from repo to repoid for now.