[test] fix stage config for k8s tests (#5336)
[test] fix stage config for k8s tests (#5336)

- python is not available/needed on k8s images
h2oai/h2o-3,h2oai/h2o-3,h2oai/h2o-3,michalkurka/h2o-3,h2oai/h2o-3,michalkurka/h2o-3,michalkurka/h2o-3,michalkurka/h2o-3,h2oai/h2o-3,h2oai/h2o-3,michalkurka/h2o-3,michalkurka/h2o-3,michalkurka/h2o-3,h2oai/h2o-3,h2oai/h2o-3