kdefrontend/dockwidgets replace "QStringLiteral("")" with "QString()"
Fix clazy issue "warning: Use an empty QLatin1String instead of an empty QStringLiteral [clazy-empty-qstringliteral]".
Fix clazy issue "warning: Use an empty QLatin1String instead of an empty QStringLiteral [clazy-empty-qstringliteral]".