UI files: use notr="true" instead of old comment="KDE::DoNotExtract"
Usage of "KDE::DoNotExtract" predates the notr attribute and still results in uic generating code trying to do a (bogus) lookup for the very string.
With notr attribute instead the generated code will only set the given string as-is. While the given strings are just sample text to help when working on the UI file and ideally would not appear at all in the final product, this here at least fixes the also unneeded translation call.