centos: Handle major/minor releases in derivatives properly

centos: Handle major/minor releases in derivatives properly

While centos doesn't have major/minor releases, rocky, alma and rhel
do, so let's make sure we handle those cases properly.

Additionally, we also fix EPEL to use the proper major/minor release
when we're doing EPEL 10, as since EPEL 10 there's major/minor releases
for EPEL as well.