Orchestrator: Scheduled task for docker environment mainenance

* To reduce build times we should periodically pull supported images (e.g. ubuntu:latest, openjdk:11 etc.) * Related to #344, those base images can be built periodically in the background too (like, combination of SDK + version + APT dependencies) ^ Irrelevant because we are now using images from ghcr.io

• We keep getting an error with EOF on docker pull from time to time, which can be fixed with docker logout, which does nothing, because we are using public registries, but still is able to fix stuff. It should be done periodically as well.