Could have been done in e32554cd57, but I
skipped it there. However, using viewporter is actually a win here.
There's been a longstanding issue in upstream wayland* exactly related
to this. I even forgot about cd7a7a1de8
which was made for this exactly problem and explains the random
spawn_cursor calls. Anyways, just not using buffer scale and instead
scaling the cursor surface via viewporter works just fine and completely
sidesteps this problem. This means we can drop the random looking
spawn_cursor calls and some additional checks.
*: https://gitlab.freedesktop.org/wayland/wayland/-/issues/194
f0a6578259