Our finalizers are not domain-qualified, and therefore do not conform to requirements

What steps did you take and what happened?

Identifiers of custom finalizers consist of a domain name, a forward slash and the name of the finalizer. -- https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions/#finalizers

Our finalizers are not domain-qualified.

For example, our Cluster finalizer is cluster.cluster.x-k8s.io. To make it domain-qualified, we could change it cluster.x-k8s.io/cluster.

What did you expect to happen?

• The Cluster API core finalizers should be domain-qualified.
• We should also guide community providers to make their finalizers domain-qualified.

Cluster API version

v1.7.3

Kubernetes version

Server Version: v1.29.6

Anything else you would like to add?

After https://github.com/kubernetes/kubernetes/issues/119445 merged, and released in v1.29.0, the API server began to return a warning whenever the client creates a Custom Resource with a finalizer that is not domain-qualified.

Cluster API users who use Kubernetes v1.29.0 or newer can expect to find these warnings when our controllers add finalizers to resources, and when we execute clusterctl move, which creates Custom Resources with finalizers on the target cluster.

Examples of warnings

> ./clusterctl move --kubeconfig=src.kubecconfig --to-kubeconfig=dst.kubeconfig
Performing move...
Discovering Cluster API objects
Moving Cluster API objects Clusters=1
Moving Cluster API objects ClusterClasses=1
Waiting for all resources to be ready to move
Creating objects in the target cluster
[KubeAPIWarningLogger] metadata.finalizers: "addons.cluster.x-k8s.io": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers
[KubeAPIWarningLogger] metadata.finalizers: "addons.cluster.x-k8s.io": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers
[KubeAPIWarningLogger] metadata.finalizers: "addons.cluster.x-k8s.io": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers
[KubeAPIWarningLogger] metadata.finalizers: "addons.cluster.x-k8s.io": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers
[KubeAPIWarningLogger] metadata.finalizers: "cluster.cluster.x-k8s.io": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers
[KubeAPIWarningLogger] metadata.finalizers: "dockercluster.infrastructure.cluster.x-k8s.io": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers
[KubeAPIWarningLogger] metadata.finalizers: "kubeadm.controlplane.cluster.x-k8s.io": prefer a domain-qualified finalizer name to avoid accidental conflictswith other finalizer writers
[KubeAPIWarningLogger] metadata.finalizers: "machine.cluster.x-k8s.io": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers
[KubeAPIWarningLogger] metadata.finalizers: "machine.cluster.x-k8s.io": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers
[KubeAPIWarningLogger] metadata.finalizers: "dockermachine.infrastructure.cluster.x-k8s.io": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers
[KubeAPIWarningLogger] metadata.finalizers: "dockermachine.infrastructure.cluster.x-k8s.io": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers
Deleting objects from the source cluster 

> kubectl logs -n capi-system capi-controller-manager-6db447f75f-kp94j | grep -i warning
I0719 17:41:28.440401       1 warning_handler.go:65] "metadata.finalizers: \"cluster.cluster.x-k8s.io\": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers" logger="KubeAPIWarningLogger"
I0719 17:41:28.546145       1 warning_handler.go:65] "metadata.finalizers: \"addons.cluster.x-k8s.io\": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers" logger="KubeAPIWarningLogger"
I0719 17:41:28.775619       1 warning_handler.go:65] "metadata.finalizers: \"machine.cluster.x-k8s.io\": prefer a domain-qualified finalizer name to avoid accidental conflicts with other finalizer writers" logger="KubeAPIWarningLogger"

Label(s) to be applied

/kind bug One or more /area label. See https://github.com/kubernetes-sigs/cluster-api/labels?q=area for the list of labels.