shrink-rgw: refact global workflow
shrink-rgw: refact global workflow

Instead of running the ceph roles against localhost we should do it
on the first mon.
The ansible and inventory hostname of the rgw nodes could be different.
Ensure that the rgw instance to remove is present in the cluster.
Fix rgw service and directory path.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1677431

Signed-off-by: Dimitri Savineau <a50a620e679eed14f4e99998b821cea8884cf228@redhat.com>

ceph/ceph-ansible,ceph/ceph-ansible