config: ensure rgw section has the correct name

config: ensure rgw section has the correct name

the ceph.conf.j2 always assumes the hostname used to register the
radosgw in the servicemap is equivalent to `{{ ansible_hostname }}`
which returns the shortname form.

We need to detect which form of the hostname was used in case of already
deployed cluster and update the ceph.conf accordingly.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1580408
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>