Review Build Image Build Process

[drewbo]

In conjunction with #248 we should review what is included in the build image and how it is built. In particular:

• Chrome (used for puppeteer) is included in every build container despite not currently being used (the template repositories contain pa11y-ci which relies on puppeteer but it is run via GitHub actions). This makes M1 docker builds difficult, slows down the build, and adds 450MB to the final image.
• Sometimes the RVM GPG keyservers fail the build on CI for no apparent reason. There isn't an easy way to add rvm without this but we should consider only having certain versions of ruby available (and using separate images) rather than allowing an install at runtime.

Acceptance Criteria

• Conduct build review
• Ticket outstanding items
• Replace this issue and Garden Build / Proxy Architecture Improvements #248 which are more general

[drewbo]

Reiterating the second point here that we should reconsider how we handle language versions (i.e. can we support multiple build images rather than switching the version at runtime), especially in light of #412

[drewbo]

Here's the first step in using multiple containers/images: cloud-gov/pages-builder#550