PSA: gibba nodes are again available for teuthology jobs

The long-running upgrade cluster has been retired. https://pulpito.ceph.com/?machine_type=gibba For information about the gibba hardware, see: https://wiki.sepia.ceph.com/doku.php?id=hardware:gibba -- Patrick Donnelly, Ph.D. He / Him / His Red Hat Partner Engineer IBM, Inc. GPG: 19F28A586F808C2402351B93C3301A3E258DD79D