Fix `I18N_ARGUMENT_MISSING` error with the progress bar.

This fixes the issue I wrote about in https://bugs.kde.org/show_bug.cgi?id=477931

Going by the documentation of QProgressBar the default progress format key is %p%. %1% may have worked in QT5 (unconfirmed) but it no longer works in QT6. (At least on my machine!)

I'm unsure how to extract text, or if that's handled automatically by a ci. Feel free to point me in the right direction for that and I can fix up the .po files!

Before:

After:

Cheers