[Usability] Possible to provide an option or a sugeestion in KScreen to (guide the user to) enable "PLASMA_USE_QT_SCALING"?

[David Edmundson]

>(But where should the setting be saved? "~/.profile" or a config file
like "startkderc"? The latter may require modifying

If a problem is hard to solve, change the problem.

It's an environment variable because that was a good tool for the
problem it was solving at the time. But there's no reason why it has
to stay as one. If we do end up doing this instead of doing messy
things with the env, get rid of the env completely and change the
logic in plasmashell/krunner to be "if (wayland ||
someConfig.readEntry(..)".