Add e2e tests to openshift/origin to test the improvement in integration between CoreDNS and EgressFirewall as proposed in the enhancement https://github.com/openshift/enhancements/pull/1335.

As the feature is currently targeted for Tech-Preview, the e2e tests should enable the feature set to test the feature.

The e2e test should create EgressFirewall with DNS rules after enabling Tech-Preview. The EgressFirewall rules should work correctly. E.g. https://github.com/openshift/origin/blob/master/test/extended/networking/egress_firewall.go