Build (or consider reuse of) a docker image that can be used to run QA tests

Summary

This issue concerns checking if one of the existing images can replace some of the build implemented in a PoC running QA tests on GDK in CI.

If not, this issue will track the work needed to create that image.

We should also consider how to optimally build images so that tests in MR pipelines can be started as quickly as possible. Specifically, GDK will run in a container in MRs in gitlab-org/gitlab.

Questions

• Can we use a docker image in a way that lets a CI job check out GitLab into the container and start GDK using the checked out code?
  • E.g., a volume mount using docker-in-docker, or just use the image to run the job and make sure GDK uses the code that gets checked out.
  • Can we do that while minimizing both the size of the image and the time it takes to get GDK ready to serve requests?
• How, and how frequently are the docker images updated?
• Is there any other work that involves using GDK docker images that we might be duplicating (e.g., Gitpod)?
• Do we have any documentation on the ways that GDK differs from production environments? (including differences like the way assets are handled that meant we let a bug through)

Tasks

• Determine which of the docker images are closest to the final stage of the PoC image
• Use the image identified ☝ as the first stage when running QA tests instead of installing GDK on top of asdf-bootstrapped-verify:main.
• Create the image and an appropriate build schedule in this project: !2928 (merged)