build: Rewrite circleci steps

[ozamosi]

This is effectively 3 different changes:

• Increase the lowest tested versions. Old clusters have races and spurious failures.
• Use some newer circleci features (commands and parameters) to avoid some of the clever yaml usage, because we got the clever yaml usage wrong.
• Swap minikube for kind - kind export logs is brilliant. This does mean losing out on minikube service but, eh.