Update ILIAS installation

We are targeting v5.4

• Revisit (Installing ILIAS from scratch)[https://www.ilias.de/docu/goto.php?target=pg_6488&client_id=docu] to have a look at what an initial installation looks like
• Update Dockerfile(s)
• Check upgrade procedure

We are working towards a local v2.0-release with

• helm to produce k8s.yaml files
• backup (semi-)integration
• tbd