Consider if to add more on KCP checks on machine status

### What would you like to be added (User Story)?

As an operator, I need as much as possible info about the status of my control plane machines

### Detailed Description

KCP implements checks for components status on controlled machines: API Server, Scheduler, Controller Manager, etcd

We should consider if to add more to the list of components, e.g. kube-proxy, kubelet (node).
This could provide an interesting signal to catch problems that could happen during upgrades when e.g. the control plane comes up because it is implemented via static pod, but other "regular" pods scheduled on the control plane node might not come up.

### Anything else you would like to add?

_No response_

### Label(s) to be applied

/kind feature
/area provider/control-plane-kubeadm

Start by reviewing the existing KCP checks for API Server, Scheduler, Controller Manager, and etcd, then trace where their status is collected and reported. Define which additional kube-proxy or kubelet checks are in scope and how their results should signal control-plane machine health; completion requires an agreed scope and corresponding implementation and tests.

Written by the indexing model from the issue text.