The docker image is nowhere to be found, so lets remove it.
There have been a request for the Dockerfile here [1], but nobody
seems to care.

redis-proxy is replaced with redis-master in test-cmd-util.sh, to
ensure that the tests still works.
The redis-proxy pod in test/fixtures/doc-yaml/user-guide/multi-pod.yaml
is replaced with valid-pod from test/fixtures/doc-yaml/admin/limitrange/valid-pod.yaml,
so redis-proxy is removed every where.

[1] https://github.com/kubernetes/kubernetes/issues/4914#issuecomment-77209779