Build images in the Fedora Konflux instance

This issue is tracking using Fedora Konflux to build our base images.

https://discussion.fedoraproject.org/t/containers-sig-for-konflux-discussions/128061 now exists.

We should start using it and also at least work on deduplicating build pipelines and release engineering work across fedora/centos/rhel.

Part of #1

---

Update 20250412: There are now development builds built in Fedora Konflux: https://gitlab.com/fedora/bootc/base-images#available-tiers--versions