config: set default _rgw_hostname value to respective host
config: set default _rgw_hostname value to respective host

the default value for _rgw_hostname was took from the current node being
played while it should be took from the respective node in the loop.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1622505

Signed-off-by: Guillaume Abrioux <30a9df5a0293a6108675377fa1673f7aa713f915@redhat.com>
(cherry picked from commit 6d6fd514e0cbfb8283c349353582966938cd1c10)

fgal/ceph-ansible,fgal/ceph-ansible