rgw: fix multi instances scaleout in baremetal

rgw: fix multi instances scaleout in baremetal

When rgw and osd are collocated, the current workflow prevents from
scaling out the radosgw_num_instances parameter when rerunning the
playbook in baremetal deployments.

When ceph-osd notifies handlers, it means rgw handlers are triggered
too. The issue with this is that they are triggered before the role
ceph-rgw is run.
In the case a scaleout operation is expected on `radosgw_num_instances`
it causes an issue because keyrings haven't been created yet so the new
instances won't start.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1881313
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>