copr builders moved to F31, with more builders

Hey all,

Jakub recently finished movement of copr builders from Fedora 30 to Fedora
F31. At this moment we are not aware of any serious issues related to
this change, but please let us know if you noticed anything.

With a great help of fedora infra (Kevin) we were able to add a new set of
builders for x86_64 architecture, so the build queue processing should be
faster now. Also, the new machines should be a bit faster (while we still
keep the old machines), so please be prepared that the x86_64 builder set
is not that homogeneous as before. There's currently no way to pick VM
from one or another set.

Happy building!