mgr/cephadm: don't treat unknown daemon state as error

mgr/cephadm: don't treat unknown daemon state as error

cephadm ls may transiently report state='unknown' for daemons that are
still starting up. The state mapping in _refresh_host_daemons mapped
'unknown' to DaemonDescriptionStatus.error, which caused
update_failed_daemon_health_check to fire CEPHADM_FAILED_DAEMON for
daemons that were simply mid-startup. The warning clears on the next
refresh once the daemon reaches a real state, but it causes spurious
QA failures across many test suites.

Map 'unknown' to DaemonDescriptionStatus.unknown instead — the enum
value already exists and is handled by to_str() and the dashboard.
get_error_daemons() only checks for .error, so unknown daemons no
longer trigger the health warning.

Signed-off-by: Lumir Sliva <61183145+lumir-sliva@users.noreply.github.com>