fixes overzealous deletion of SNAT in egressIP

currently when creating egressIP in a dualstack cluster regardless of if
the egressip is ipv4 or ipv6 when disable-snat-multiple-gws is set the
code removes both ipv4 and ipv6 snats from the database. This means that
the pod will not be able to communicate with the cluster correctly
becuase the Gateway Router is missing an SNAT and the traffic will be
dropped.

Additionally the testing looks a little different from the others
because we do not correctly setup dualstack clusters when running unit
tests

Signed-off-by: Jacob Tanenbaum <jtanenba@redhat.com>

go-controller/pkg/ovn/egressip.go

@@ -1674,13 +1674,17 @@ func (e *egressIPZoneController) addExternalGWPodSNATOps(ops []ovsdb.Operation,
 // deleteExternalGWPodSNATOps creates ops for the required external GW teardown for the given pod
 func (e *egressIPZoneController) deleteExternalGWPodSNATOps(ops []ovsdb.Operation, pod *kapi.Pod, podIPs []*net.IPNet, status egressipv1.EgressIPStatusItem, isOVNNetwork bool) ([]ovsdb.Operation, error) {
 	if config.Gateway.DisableSNATMultipleGWs && status.Node == pod.Spec.NodeName && isOVNNetwork {
+		affectedIPs := util.MatchAllIPNetFamily(utilnet.IsIPv6String(status.EgressIP), podIPs)
+		if len(affectedIPs) == 0 {
+			return nil, nil // noting to do.
+		}
 		// remove snats to->nodeIP (from the node where pod exists if that node is also serving
 		// as an egress node for this pod) for these podIPs before adding the snat to->egressIP
 		extIPs, err := getExternalIPsGR(e.watchFactory, pod.Spec.NodeName)
 		if err != nil {
 			return nil, err
 		}
-		ops, err = deletePodSNATOps(e.nbClient, ops, e.GetNetworkScopedGWRouterName(pod.Spec.NodeName), extIPs, podIPs, "")
+		ops, err = deletePodSNATOps(e.nbClient, ops, e.GetNetworkScopedGWRouterName(pod.Spec.NodeName), extIPs, affectedIPs, "")
 		if err != nil {
 			return nil, err
 		}
@@ -1806,6 +1810,7 @@ func (e *egressIPZoneController) createReroutePolicyOps(ops []ovsdb.Operation, p
 	var err error
 	// Handle all pod IPs that match the egress IP address family
 	for _, podIPNet := range util.MatchAllIPNetFamily(isEgressIPv6, podIPNets) {
+
 		lrp := nbdb.LogicalRouterPolicy{
 			Match:    fmt.Sprintf("%s.src == %s", ipFamilyName(isEgressIPv6), podIPNet.IP.String()),
 			Priority: types.EgressIPReroutePriority,