Default to light mode, where AppsUseLightTheme isn't set (notably Windows 8.1)
See https://mail.kde.org/pipermail/kde-core-devel/2022-March/091597.html
Tested on Windows 8.1 virtual machine, and defaults to light mode, as expected, now.
See https://mail.kde.org/pipermail/kde-core-devel/2022-March/091597.html
Tested on Windows 8.1 virtual machine, and defaults to light mode, as expected, now.