Avoid git clones during deployment by creating pre-cloned tagged container

As a leftover from our old style of pulling 'latest' of all components when we deploy, the install-packages-job, system-test-job, and init-couchdb-job all clone one or more git repos as part of their computation. The system-test-job also scalaCompiles the test suite, which really should be done at build time.

Instead of doing this, we should create a single docker image that extends ow-utils and does all the git clones with the specified githash at build time. We can update this image periodically (at the same time as we update the other tags in values.yaml and runtimes.json).

This would make deployment a little faster and also remove an occasional source of deployment failures when github is unresponsive and the clone fails.

Start by locating install-packages-job, system-test-job, and init-couchdb-job, then inspect values.yaml and runtimes.json alongside the ow-utils image setup. The finished change should provide one tagged image that performs the specified git clones and Scala test compilation at build time, so deployment jobs no longer clone or compile during deployment.

Written by the indexing model from the issue text.