Downscaling: mon config not removed

[sabaini]

Issue report

What version of MicroCeph are you using ?

19.2.0+snape32ad499ad

What are the steps to reproduce this issue ?

1. deploy a two node cluster (no OSD req)
2. remove one node sudo microceph cluster remove --force juju-bea517-4

What happens (observed behaviour) ?

While sudo microceph status says there's only one node present anymore we still have mon entries in the db, and therefore are also rendered into ceph conf

sudo microceph cluster sql "select * from config where key like 'mon.host.%'"
+----+------------------------+---------------+
| id |          key           |     value     |
+----+------------------------+---------------+
| 3  | mon.host.juju-bea517-4 | 10.56.169.27  |
| 5  | mon.host.juju-bea517-5 | 10.56.169.114 |
+----+------------------------+---------------+

grep mon /var/snap/microceph/current/conf/ceph.conf 
mon host = 10.56.169.27,10.56.169.114

What were you expecting to happen ?

Config db being pruned, ceph.conf not referring to removed node