Print message after successfully connecting to a K8s cluster

[Techassi]

No description provided.

[soenkeliebau]

To add some context here, I frequently run into an issue when I use stackablectl with an old kubeconifg, where it stays silent for a while and I expect it connected succesfully and go away to do something else. But when I return it printed an error about not being able to connect to k8s.

This is helped by the fact, that a successful stackablectl run stays "silent" for a very long time, so users need to "guess" when it actually started doing work.