refactor: consistently use the same SetOwnerReference function (#713)

**What problem does this PR solve?**:
Follow up to
https://github.com/nutanix-cloud-native/cluster-api-runtime-extensions-nutanix/pull/711/files
😞

Realized that everywhere else we use this function instead. Unit tests
are unchanged, and verified manually too that it all still works:
```
  kind: Secret
  metadata:
    creationTimestamp: "2024-06-11T16:19:52Z"
    labels:
      cluster.x-k8s.io/provider: nutanix
    name: dkoshkin-nkp-secrets-ownership-7-pc-creds-for-csi
    namespace: default
    ownerReferences:
    - apiVersion: cluster.x-k8s.io/v1beta1
      kind: Cluster
      name: dkoshkin-nkp-secrets-ownership-7
      uid: fd102035-5f0b-4185-92d3-b08c251b775c
```

**Which issue(s) this PR fixes**:
Fixes #

**How Has This Been Tested?**:
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pkg/handlers/generic/lifecycle/utils/secrets.go

@@ -11,8 +11,8 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	clusterv1 "sigs.k8s.io/cluster-api/api/v1beta1"
 	"sigs.k8s.io/cluster-api/controllers/remote"
-	"sigs.k8s.io/cluster-api/util"
 	ctrlclient "sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
 
 	"github.com/nutanix-cloud-native/cluster-api-runtime-extensions-nutanix/common/pkg/k8s/client"
 )
@@ -75,15 +75,10 @@ func EnsureOwnerRefForSecret(
 		return err
 	}
 
-	secret.OwnerReferences = util.EnsureOwnerRef(
-		secret.OwnerReferences,
-		metav1.OwnerReference{
-			APIVersion: clusterv1.GroupVersion.String(),
-			Kind:       cluster.Kind,
-			UID:        cluster.UID,
-			Name:       cluster.Name,
-		},
-	)
+	err = controllerutil.SetOwnerReference(cluster, secret, cl.Scheme())
+	if err != nil {
+		return fmt.Errorf("failed to set owner reference on Secret: %w", err)
+	}
 
 	err = cl.Update(ctx, secret)
 	if err != nil {