There are two ways of building kubemark: 1) via Dockerfile and 2) via
bazel.
In CI/CD tests we use the 1) way and use debian:jessie as the base
image.
But if you build kubemark via bazel it will use the discouraged busybox
base image.
This PR fixes that by using debian:jessie everywehre and pinning exact
sha version to make the kubemark image hermetic.
686245b876