Don’t extract QML text as Java strings

Extracting the strings as Java strings causes the string ‘%1%’ to be marked as ‘java-printf-format’ in the translation file. The result is that it can’t be properly translated in all languages, e.g., into ‘%1 %’ for languages which require a space in front of the percentage sign.

See https://mail.kde.org/pipermail/kde-i18n-doc/2021-March/000450.html and plasma-workspace!711 (merged) for more details.