Kubeadm: Automate certificate copy between control planes in HA setups

- Joining control plane nodes to a HA cluster can now be simplified by enabling the optional automatic copy of certificates from an existing control plane node.
- You can now use `kubeadm init --experimental-upload-certs` and `kubeadm join --experimental-control-plane --certificate-key`.

configuration file, that gets forwarded to kubelet static pods to control pull policy for etcd and control plane images. This option allows for precise image pull policy specification for master nodes and thus for more tight control over images. It is useful in CI environments and in environments, where the user has total control over master VM templates (thus, the master VM templates can be preloaded with the required Docker images for the control plane services). ([#58960](https://github.com/kubernetes...

- Restores priority of static control plane pods in the cluster/gce/manifests control-plane manifests ([#89970](https://github.com/kubernetes/kubernetes/pull/89970), [@liggitt](https://github.com/liggitt)) [SIG Cluster Lifecycle and Node]

### Other (Cleanup or Flake)

release.  A new alpha feature is introduced to improve the mechanism that nodes heartbeat back to the control plane.  The `NodeLease` feature results in the node using a `Lease` resource in the `kube-node-lease` namespace that is renewed periodically.  The `NodeStatus` that was used previously to heartbeat back to the control plane is only updated when it changes.  This reduces load on the control plane for large clusters. The Kubelet plugin registration mechanism, which enables automatic discovery...

ControlPlaneKubeletLocalMode feature gate. It can be used to tell kubeadm to use the local kube-apiserver endpoint for the kubelet when creating a cluster with "kubeadm init" or when joining control plane nodes with "kubeadm join".  The "kubeadm join" workflow now includes two new experimental phases called "control-plane-join-etcd" and "kubelet-wait-bootstrap" which will be used when the feature gate is enabled. This phases will be marked as non-experimental when ControlPlaneKubeletLocalMode becomes...

  - The `kubeadm upgrade node config` and `kubeadm upgrade node experimental-control-plane` commands are deprecated in favor of `kubeadm upgrade node`, and will be removed in a future release. ([#78408](https://github.com/kubernetes/kubernetes/pull/78408), [@fabriziopandini](https://github.com/fabriziopandini))

- github.com/bufbuild/protovalidate-go: [v0.9.1](https://github.com/bufbuild/protovalidate-go/tree/v0.9.1)
- github.com/envoyproxy/go-control-plane/envoy: [v1.32.4](https://github.com/envoyproxy/go-control-plane/tree/envoy/v1.32.4)
- github.com/envoyproxy/go-control-plane/ratelimit: [v0.1.0](https://github.com/envoyproxy/go-control-plane/tree/ratelimit/v0.1.0)
- github.com/go-jose/go-jose/v4: [v4.0.4](https://github.com/go-jose/go-jose/tree/v4.0.4)

  - Make "kubeadm upgrade apply" add the "node-role.kubernetes.io/control-plane" label on existing nodes that only have the "node-role.kubernetes.io/master" label during upgrade.
  - Please adapt your tooling built on top of kubeadm to use the "node-role.kubernetes.io/control-plane" label.
  - The taint applied to control-plane nodes "node-role.kubernetes.io/master:NoSchedule" is now deprecated and will be removed in a future release after a GA deprecation period.

### Deploy a more secure control plane with kubeadm

A new alpha feature allows running the kubeadm control plane components as non-root users. This is a long requested security measure in kubeadm. To try it you must enable the kubeadm-specific `RootlessControlPlane` feature gate. When you deploy a cluster using this alpha feature, your control plane runs with lower privileges.

- kubeadm: Promoted the feature gate `ControlPlaneKubeletLocalMode` to Beta. By default, kubeadm will use the local kube-apiserver endpoint for the kubelet when creating a cluster with `kubeadm init` or when joining control plane nodes with `kubeadm join`. Enabling the feature gate also affects...