The ovirt compute resource model has the option to skip fog and connect to rbovirt directly:
https://github.com/theforeman/foreman/blob/develop/app/models/compute_resources/foreman/model/ovirt.rb#L488

Fog should hide the use of rbovirt completely to allow moving from rbovirt to something that can connect to ovirt api v4.
This needs 2 changes:
1) In Fog - make sure anything that uses rbovirt directly exists in Fog
2) In Foreman - remove rbovit_client and change all it's uses to connect to Fog.