Enable building leapp for specific chroots only

[fernflower]

Instead of building for all project chroots use -r/--chroot option to specify chroots. Tmt-tests workflow and copr-build workflow will be passing proper chroots now via COPR_CHROOT env var. Also some refactoring has been done to the workflows to move all magic constants to env section.

OAMG-6735

[centos-ci]

Can one of the admins verify this patch?

[github-actions[bot]]

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[fernflower]

My bad, leapp is supposed to be built everywhere. So closing this and will limit chroots for leapp-repository only