Avoid re-downloading several times the same artifacts

Summary

In order to avoid re-downloading several times the same artifacts, and to allow to search in artifacts that were previously downloaded, it would be convenient to append the job-id to the artifact name.

Gitlab has that capability: https://docs.gitlab.com/ee/ci/jobs/job_artifacts.html#with-a-dynamically-defined-name

This should be fairly simple, but would require a small adaptation of download_artifact function.