Reduce prod container size

See merge request !1

- /docker/latest/Dockerfile.dockerignore
- /.gitlab-ci.yml

Remove log file in test: we want warnings to be outputed so developpers see them and have to deal with it

Refactor logging to be printed if a log file is not provided, and add logging file and log level arguments to dl1_to_dl2

This reverts commit e44f17b2