Fix delete pool lead to panic

1) seems we don't need port 22, have no idea why use here
2) when pool not exist, should check and ignore following actions

Author: jichenjc

pkg/cloud/openstack/machine/actuator.go

@@ -228,7 +228,7 @@ func (a *Actuator) Delete(ctx context.Context, cluster *clusterv1.Cluster, machi
 	}
 
 	if clusterProviderSpec.ManagedAPIServerLoadBalancer {
-		err = networkingService.DeleteLoadBalancerMember(clusterName, machine, clusterProviderStatus)
+		err = networkingService.DeleteLoadBalancerMember(clusterName, machine, clusterProviderSpec, clusterProviderStatus)
 		if err != nil {
 			return err
 		}

pkg/cloud/openstack/services/networking/loadbalancer.go

@@ -264,7 +264,7 @@ func (s *Service) ReconcileLoadBalancerMember(clusterName string, machine *clust
 	return nil
 }
 
-func (s *Service) DeleteLoadBalancerMember(clusterName string, machine *clusterv1.Machine, clusterProviderStatus *providerv1.OpenstackClusterProviderStatus) error {
+func (s *Service) DeleteLoadBalancerMember(clusterName string, machine *clusterv1.Machine, clusterProviderSpec *providerv1.OpenstackClusterProviderSpec, clusterProviderStatus *providerv1.OpenstackClusterProviderStatus) error {
 
 	if machine == nil || !util.IsControlPlaneMachine(machine) {
 		return nil
@@ -274,14 +274,20 @@ func (s *Service) DeleteLoadBalancerMember(clusterName string, machine *clusterv
 
 	lbID := clusterProviderStatus.Network.APIServerLoadBalancer.ID
 
-	for _, port := range []int{22, 6443} {
+	portList := []int{clusterProviderSpec.APIServerLoadBalancerPort}
+	portList = append(portList, clusterProviderSpec.APIServerLoadBalancerAdditionalPorts...)
+	for _, port := range portList {
 		lbPortObjectsName := fmt.Sprintf("%s-%d", loadBalancerName, port)
 		name := lbPortObjectsName + "-" + machine.Name
 
 		pool, err := checkIfPoolExists(s.client, lbPortObjectsName)
 		if err != nil {
 			return err
 		}
+		if pool == nil {
+			klog.Infof("Pool %s does not exist", lbPortObjectsName)
+			continue
+		}
 
 		lbMember, err := checkIfLbMemberExists(s.client, pool.ID, name)
 		if err != nil {