kcms/cursortheme: Fix cursor size preview
On wayland the cursor size is in logical pixels, so don't divide by the device pixel ratio.
Respect the actual icon size, which is different from the cursor size.
BUG: 478089 FIXED-IN: 6.0
Depends on frameworks/kirigami!1440 (merged)
I would appreciate it if someone could check this on both X11 and wayland, thanks!
Edited by Yifan Zhu