Add backwards compatibility for kubectl debug
Add backwards compatibility for kubectl debug

The ephemeral containers API changed in 1.22. As a result, kubectl
debug (currently) cannot create ephemeral containers in clusters prior
to 1.22.

This change causes kubectl to retry the request using the old API when
it receives a specific error message from the server.

Kubernetes-commit: 06124c1d1c68ec4a30406bf585df2ec83231cb65

kubernetes/kubectl,kubernetes/kubectl