ceph-mon: Don't set monitor directory mode recursively

ceph-mon: Don't set monitor directory mode recursively

After rolling updates performed with
`infrastructure-playbooks/rolling_updates.yml`, files located in
`/var/lib/ceph/mon/{{ cluster }}-{{ monitor_name }}` had mode 0755 (including
the keyring), making them world-readable.

This commit separates the task that configured permissions recursively on
`/var/lib/ceph/mon/{{ cluster }}-{{ monitor_name }}` into two separate tasks:

1. Set the ownership and mode of the directory itself;
2. Recursively set ownership in the directory, but don't modify the mode.

Signed-off-by: Benoît Knecht <bknecht@protonmail.ch>