Testability for scap!478

Add a deployer01 user to the deploy container. This user is a
member of the wikidev and deployment groups, but not the docker
group.

To log in to the deploy container as this user:

./train-dev ssh -u deployer01 deploy  

Other notable changes:

• Added sudoers rules for deployment group to run scap mwshell and scap mwscript
  as mwbuilder.

• Set docker_user and release_repo_build_and_push_images_cmd in
  scap.cfg.

• Set up helm stuff (such as repo definitions and plugins) in a shared
  place that can be used by all users on the system, as is done in
  production.