Makefile/cloudbuild.yaml cleanup

[ianlewis]

A lot of build steps are duplicated in Makefile and cloudbuild.yaml. These could be cleaned up and unified.

[ianlewis]

We are now using the same Docker images for running commands as we are in cloudbuild after #128 .

You can run cloud build locally with the cloud-build-local tool but you can't run individual commands and it requires that you install gcloud in order to install it.

There doesn't seem to be a good way to de-duplicate commands without combining all the cloud build steps into a single step. Maybe creating a single big image with all dependencies installed and running commands using that image is the best option?