text: Title: test/soak/cauldron uses Docker Hub to push/pull image
  Body: We've deleted all repos from Docker Hub and will be retiring the org/user (ref: https://github.com/kubernetes/k8s.io/issues/237)
  
  Apparently the `kubernetes/cauldron` repo is referenced for docker push and pull in https://github.com/kubernetes/kubernetes/blob/master/test/soak/cauldron/Dockerfile
  
  It's unclear to me whether we have broken anything, or if this is dead code.  I would use https://cs.k8s.io to find out if this is referenced anywhere (aside from sundry vendor dirs)
  
  If dead code: remove it
  
  If used: move to test/e2e/images and follow the same pattern there used to push to gcr.io
  
  /sig testing
  /area test
  /wg k8s-infra
  /priority important-soon
  
  /help
  /good-first-issue
  I believe this is a pretty straightforward issue and am happy to review whatever PR's are made for it