WIP: [kubernetes] Switch to client-go

This is a general Merge Request template. Consider to choose a template from the list above if it will match your case more.

What does this MR do?

This MR attempts to switch us to using kubernetes/client-go instead of kubernetes/kubernetes for calls to Kubernetes, in order to reduce binary & repository size.

This is incomplete as the exec.go file is not switched over yet.

Why was this MR needed?

Reduce binary & repo size. Bring calls to k8s up to date (client-go is now the recommended way to talk to k8s)

Are there points in the code the reviewer needs to double check?

Currently incomplete

Does this MR meet the acceptance criteria?

  • Documentation created/updated
  • Tests
    • Added for this feature/bug
    • All builds are passing
  • Branch has no merge conflicts with master (if you do - rebase it please)

What are the relevant issue numbers?