Without upgrading the zone with forwarders are not converted into forwardzones.

If user just add new IPA 4.0+ replica, zones will not be updated, and forwarding will not happening in IPA 4.0+ replicas.

Note: this upgrade should be executed only once, with detection if there indsforwardzone objectclass exists, so adding new replica and then upgrade old, will not migrate the zones into forwardzones.