cephadm: fix osd adoption with custom cluster name

[guits]

When adopting Ceph OSD containers from a Ceph cluster with a custom name, it fails
because the name isn't propagated in unit.run.
The idea here is to change the lvm metadata and enforce 'ceph.cluster_name=ceph'
given that cephadm doesn't support custom names anyway.

Fixes: https://tracker.ceph.com/issues/55654

Signed-off-by: Adam King adking@redhat.com
Co-authored-by: Guillaume Abrioux gabrioux@redhat.com

[adk3798]

https://pulpito.ceph.com/adking-2022-06-02_01:28:06-orch:cephadm-wip-adk-testing-2022-06-01-1756-distro-default-smithi/

1 infra/teuthology failure:

{'smithi039.front.sepia.ceph.com': {'_ansible_no_log': False, 'attempts': 24, 'changed': False, 'invocation': {'module_args': {'allow_unauthenticated': False, 'autoclean': False, 'autoremove': False, 'cache_valid_time': 0, 'deb': None, 'default_release': None, 'dpkg_options': 'force-confdef,force-confold', 'force': False, 'force_apt_get': False, 'install_recommends': None, 'only_upgrade': False, 'package': None, 'policy_rc_d': None, 'purge': False, 'state': 'present', 'update_cache': True, 'update_cache_retries': 5, 'update_cache_retry_max_delay': 12, 'upgrade': None}}, 'msg': 'Failed to update apt cache: unknown reason'}}

from before the test actually started.