ci: Present docker jobs available only if based on a protected reference

Regarding jobs:
- deploy_docker_test_image
- deploy_docker_release_sha
it doesn’t make sense to have these jobs available since
it will fail with DockerHub password missing since it’s not
running on a protected branch or tag

Brought some difficulty https://forum.duniter.org/t//10164/17

https://stackoverflow.com/questions/54901151/how-do-i-configure-gitlab-ci-jobs-to-run-on-protected-branches-only