Storage setup for c10s

Because of the way our storage is, we need to set up a new volume for c10s. We need to ensure that Koji uses it properly, composes use it properly, and whatever else that needs it uses it properly. We need to store all RPMs, build data, composes, images, etc on this new volume.

Acceptance criteria:

• Volume created (probably done)
• All servers/services/VMs/whatever using /mnt/centos have this new volume mounted properly using Ansible
• Koji set up to use this volume for c10s
• https://composes.stream.centos.org/stream-10/ uses this volume
• whatever else makes sense - TBD farrotin@redhat.com let's edit this description together. I know there's another issue (Gather requirements - CS-1452) so we'll just write the outcome of that here I guess.
• Document this setup on some permanent place for future reference

This needs to be completed before c10s builds start.

(For context, this ticket is step 2 from CS-1431)