Revert all Docker restructuring

[MattWellie]

Fixes

• I wanted to produce a skinnier base image for AIP, instead of building on the CPG driver/pipeline image
• That breaks, as all the CI-instigated processes rely on gcloud inside the images, which was the bulky library I was trying to get rid of...

Proposed Changes

• Builds on top of CPG driver/pipelines image
• CI tasks all run in the fully-fleshed out image

Checklist

• [ ] Related Issue created
• [ ] Tests covering new change
• [ ] Linting checks pass

[MattWellie]

Also spikes in a change which filters out ClinVar variants on chrUn