Refactor all our dockerfile to use our base image.

[Kevan-Y]

In https://github.com/Seneca-CDOT/telescope/issues/2803, we created a base image to be used. Base image 🔽 https://github.com/Seneca-CDOT/telescope/blob/master/src/api/Dockerfile

Once refactoring all our dockerfile https://github.com/Seneca-CDOT/telescope/issues/1668 is done. We can start replacing all dockerfile to use our base image.

Some todo:

• Push the base image to our docker registry.
• Change all our dockerfile to use that base image.

[humphd]

One question I have is about build order in CI. We build all the Dockerfiles in parallel, so I'm not clear how we deal with changing the base image at the same time. It's a bit like updating an npm package that needs to get pushed to the registry, then updating our package.json files later.

Maybe it's not worth worrying about, and we should pin the version of the base image we use by sha in Docker, and update manually (or have Renovatebot do it).