azure: enable hybrid mode for gossip clusters

Expose kops-controller on the cluster load balancer for gossip Azure
clusters with an API LB. Drop the unused UsesPrivateDNS clause.

Author: hakman

pkg/apis/kops/cluster.go

@@ -987,7 +987,7 @@ func (c *Cluster) UsesLoadBalancerForKopsController() bool {
 		return lb != nil && lb.Class == LoadBalancerClassNetwork
 	case CloudProviderHetzner:
 		return true
-	case CloudProviderDO, CloudProviderGCE, CloudProviderOpenstack, CloudProviderScaleway:
+	case CloudProviderAzure, CloudProviderDO, CloudProviderGCE, CloudProviderOpenstack, CloudProviderScaleway:
 		return c.Spec.API.LoadBalancer != nil
 	default:
 		return false

pkg/model/azuremodel/api_loadbalancer.go

@@ -104,7 +104,7 @@ func (b *APILoadBalancerModelBuilder) Build(c *fi.CloudupModelBuilderContext) er
 		return fmt.Errorf("unknown load balancer Type: %q", lbSpec.Type)
 	}
 
-	if b.Cluster.UsesLegacyGossip() || b.Cluster.UsesPrivateDNS() || b.Cluster.UsesNoneDNS() {
+	if b.Cluster.UsesLoadBalancerForKopsController() {
 		lb.WellKnownServices = append(lb.WellKnownServices, wellknownservices.KopsController)
 
 		// kops-controller probe: HTTPS on 3988 with /healthz