The microceph update config flow is not updating the `ceph.conf` file with updated mon hosts.

The `ceph.conf` file is periodically updated by a background goroutine with the updated list of mon_hosts from the dqlite db.

Observed on a fresh cluster:

```
$ cat /var/snap/microceph/current/conf/ceph.conf
# # Generated by MicroCeph, DO NOT EDIT.
[global]
run dir = /var/snap/microceph/current/run
fsid = 7dee1d8d-85d0-4e28-912c-09845592ccd5
mon host = 10.19.x.10
public_network = 10.19.x.0/24
auth allow insecure global id reclaim = false
ms bind ipv4 = true
ms bind ipv6 = false
# https://tracker.ceph.com/issues/70390
bluestore_elastic_shared_blobs = false

[client]

$ ceph config generate-minimal-conf
# minimal ceph.conf for 7dee1d8d-85d0-4e28-912c-09845592ccd5
[global]
fsid = 7dee1d8d-85d0-4e28-912c-09845592ccd5
mon_host = [v2:10.19.x.10:3300/0,v1:10.19.x.10:6789/0] [v2:10.19.x.11:3300/0,v1:10.19.x.11:6789/0] [v2:10.19.x.15:3300/0,v1:10.19.x.15:6789/0]
```

A detailed inspection is required for actual cause.