Set Docker option insecure-registry in CI and use hifis tag

* Set Docker command option --insecure-registry for the Staging
registry in the CI pipeline job, because the Staging registry has got a
self-signed certificate only.
* Add a tag hifis to select the right CI runners that support Docker in
Docker.
5 jobs for 9-test-use-case-gitlab-container-registry in 16 minutes and 17 seconds (queued for 2 seconds)