CLOUDP-235689: CI fixes for Multi-Cluster Replica Set unification feature branch (#612)

# Summary

* Removed the unused `getReplicaSetMultiClusterMap` function to make the
linter happy
* Reverted `GetMultiServiceFQDN` back to it's original version as it was
breaking a lot of unit and e2e tests.

## Proof of Work

This will break `e2e_multi_cluster_new_replica_set_scale_up` (expected
as this is a - WIP test), but fix other multi-cluster related tests for
existing APIs.

## Checklist

- [x] Have you linked a jira ticket and/or is the ticket in the title?
- [x] Have you checked whether your jira ticket required DOCSP changes?
- [x] Have you added changelog file?
    - use `skip-changelog` label if not needed
- refer to [Changelog files and Release
Notes](https://github.com/mongodb/mongodb-kubernetes/blob/master/CONTRIBUTING.md#changelog-files-and-release-notes)
section in CONTRIBUTING.md for more details

Author: m1kola

controllers/operator/mongodbreplicaset_controller_multi_test.go

@@ -97,22 +97,6 @@ func checkReplicaSetReconcileSuccessful(
 	assert.NoError(t, err)
 }
 
-// getReplicaSetMultiClusterMap simulates multiple K8s clusters using fake clients
-func getReplicaSetMultiClusterMap(omConnectionFactory *om.CachedOMConnectionFactory) map[string]client.Client {
-	clientMap := make(map[string]client.Client)
-
-	for _, clusterName := range multiClusters {
-		fakeClientBuilder := mock.NewEmptyFakeClientBuilder()
-		fakeClientBuilder.WithInterceptorFuncs(interceptor.Funcs{
-			Get: mock.GetFakeClientInterceptorGetFunc(omConnectionFactory, true, true),
-		})
-
-		clientMap[clusterName] = kubernetesClient.NewClient(fakeClientBuilder.Build())
-	}
-
-	return clientMap
-}
-
 // TestReplicaSetMultiClusterScaling tests that multi-cluster ReplicaSets scale one member at a time
 // across all clusters, similar to single-cluster behavior.
 //

pkg/dns/dns.go

@@ -37,10 +37,7 @@ func GetMultiServiceFQDN(stsName string, namespace string, clusterNum int, podNu
 		domain = strings.TrimPrefix(clusterDomain, ".")
 	}
 
-	// For StatefulSet pods, DNS format is: <pod-name>.<headless-service>.<namespace>.svc.<domain>
-	podName := GetMultiPodName(stsName, clusterNum, podNum)
-	headlessService := GetMultiHeadlessServiceName(stsName, clusterNum)
-	return fmt.Sprintf("%s.%s.%s.svc.%s", podName, headlessService, namespace, domain)
+	return fmt.Sprintf("%s.%s.svc.%s", GetMultiServiceName(stsName, clusterNum, podNum), namespace, domain)
 }
 
 func GetMultiServiceExternalDomain(stsName, externalDomain string, clusterNum, podNum int) string {