Install the minimum of dependencies and build ginkgo in release

[tpadioleau]

As a general remark, I do not think it is a good idea to introduce conditional branches inside a Dockerfile for multiple backends. I would rather recommend to prepare multiple Dockerfiles for each backend. This way each Dockerfile is significantly easier to read and maintain.

As the images tend to diverge it could be worth dedicate separate files. I also notice that modifying a single backend triggers the build of all backends which is a bit annoying. I am not against but it is not in the scope of the current PR.

[yasahi-hpc]

As a general remark, I do not think it is a good idea to introduce conditional branches inside a Dockerfile for multiple backends. I would rather recommend to prepare multiple Dockerfiles for each backend. This way each Dockerfile is significantly easier to read and maintain.

As the images tend to diverge it could be worth dedicate separate files. I also notice that modifying a single backend triggers the build of all backends which is a bit annoying. I am not against but it is not in the scope of the current PR.

I agree that this is not the scope of this PR.

[tpadioleau]

@yasahi-hpc thank you for the review