k8s / k8s-worker unit removal: delete kubernetes-related files and remove the k8s snap and the containerd deb

### Enhancement Proposal

From a current deployment, I noticed that keeping these artifacts could cause problems if I readd a unit later to the same machine

What I manually did
```
sudo snap remove --purge k8s
sudo systemctl disable containerd
sudo apt autoremove containerd
sudo rm -rf /etc/kubernetes /var/lib/containerd
```