The distribution Dockerfiles are larger than they need to be

[nicknezis]

Is your feature request related to a problem? Please describe.
The distribution Docker builds add install artifacts for Heron and Zookeeper. The files are deleted in later layers, but the size of the resulting image is still large. The user can use --squash to compress the layers and reclaim the size, but if we used multi-stage Docker builds, we could automatically make the images smaller.

Describe the solution you'd like
Use Docker multi-stage builds to install components in a base stage, and then copy over the resulting artifacts into the later stage.

Describe alternatives you've considered
Docker --squash which helps if the Docker user has the experimental feature enabled. This loses layer information.