migrate MQTT tracker to different host

Part of the DC move : mqtt.git.centos.org , used by cbs.centos.org (but also other tools) to send notifications about koji builds/tags is actually running on a el8 host in community cage, but it should be migrated asap to a different host in RDU3

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