Use the same pattern everywhere in the e2e test
harness, use busybox (from dockerhub) instead
of using the one from k8s.gcr.io registry.
Change-Id: I57c3b867408c1f9478a8909c26744ea0368ff003
utils/image/manifest has an additional `arch` parameter, which determines
whether an image ends in `-$ARCH` (like `-amd64`).
All locations that previously had gcr.io urls referenced in costants or inline
have been updated to refere test/utils/image.