v6.0.0alpha7

Changelog:

195159e library: retrieve realm id for zone/zonegroup
2734a12 cephadm-adopt: use radosgw modules for idempotency
523966d tox: test cephadm-adopt.yml playbook idempotency
ff9d314 library: make cephadm_adopt module idempotent
6886700 cephadm-adopt: make the playbook idempotent
3749d29 ceph-mon: add ExecStartPre docker stop to systemd
8617081 rgw: avoid useless call to ceph-rgw
e835b08 fs2bs: remove a legacy fact
71a5e66 rgw: multisite refact
fedb366 library: fix bug in radosgw_zone.py
959140e library: move fatal() into ca_common.py
bbcad96 grafana: update container tag to 6.7.4
7d56771 ceph-defaults: change default ceph container tag