fix(repos): Fix default package-repositories values.

Get rid of per-arch repo definitions for oracle that we cannot actually install from, since you cannot install oraclie linux without having an ISO lying around.

Get rid of the sledgehammer* repo definitions, they have not worked that way for a few major releases.

Fix up alma and rocky URLs that point at locations that are not useable anymore.

Stop using kernel.org for epel, since they cannot seem to sync up with the rest of the mirror universe. Use the same rackspace mirror everyone else uses.