Fix decommissioning steps

[haasad]

Summary

Minor improvements from exoscale 4.21 test cluster decommissioning. There's still some things that need to be improved in the next iteration, I was a bit in a rush:

• lb backups appear to not have worked
• puppet commands need to be updated to work with the new puppet infra
• cluster-backup bucket was not removed
• couple of input variables that are not needed for decommissioning (e.g. control.vshn.net token, base_domain etc.)

Checklist

• Categorize the PR by setting a good title and adding one of the labels:
  bug, enhancement, documentation, change, breaking, dependency
  as they show up in the changelog