fix: nutanix credentials Secrets owner refs

[dkoshkin]

What problem does this PR solve?:
Add ownerRef to Nutanix CSI Secret with the corresponding Cluster.

CAPX already adds an ownerRef to the PC credentials Secret that CAPX uses so did not add it there.

Which issue(s) this PR fixes:
Fixes https://jira.nutanix.com/browse/NCN-100575

How Has This Been Tested?:

Special notes for your reviewer:

[supershal]

should we add ownerrefernce use case in e2e tests? https://github.com/nutanix-cloud-native/cluster-api-runtime-extensions-nutanix/blob/main/test/e2e/ownerreference_helpers.go#L156

[dkoshkin]

should we add ownerrefernce use case in e2e tests? https://github.com/nutanix-cloud-native/cluster-api-runtime-extensions-nutanix/blob/main/test/e2e/ownerreference_helpers.go#L156

Let me run the test locally, I thought this is already being checked by this code but its just that the Nutanix e2e tests don't get run,

cluster-api-runtime-extensions-nutanix/test/e2e/ownerreference_helpers.go

Lines 180 to 195 in f1c8495

	// KubernetesReferenceAssertions maps Kubernetes types to functions which return an error if the passed OwnerReferences
	// aren't as expected.
	// Note: These relationships are documented in
	// https://github.com/kubernetes-sigs/cluster-api/tree/main/docs/book/src/reference/owner_references.md.
	KubernetesReferenceAssertions = map[string]func([]metav1.OwnerReference) error{
	secretKind: func(owners []metav1.OwnerReference) error {
	// Secrets for cluster certificates must be owned and controlled by the KubeadmControlPlane.
	// The bootstrap secret should be owned and controlled by a KubeadmControlPlane.
	// Other resources can be owned by the Cluster to ensure correct GC.
	return framework.HasOneOfExactOwners(
	owners,
	[]metav1.OwnerReference{kubeadmControlPlaneController},
	[]metav1.OwnerReference{kubeadmConfigController},
	[]metav1.OwnerReference{clusterOwner},
	)
	},

[supershal]

LGTM