migrate mailman/MX servers for centos.org to new DC

As part of the DC move, we'll have to migrate the following servers:

https://lists.stg.centos.org (Staging instance to be migrated/validated first)
https://lists.centos.org (prod instance)

Worth knowing that these are also MX records (for prod one) for centos.org so updating DNS is also required for the SFP record. To be validated before move : IP reputation of the new ipv4/ipv6 addresses we'll be given by Red Hat IT (last time we got one bad one, that was the cause of multiple mails being dropped by other ISPs)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information