Continued transition to new infrastructure setup

• Schema now has only one Dockerfile (Dockerfile.local) until we need another one.
• Schema's Docker image now uses CAPO secret rather than old docker.properties.
• Domain-model's docker-compose.yml has replaced the old ttat/docker-compose.yml.
• The other compose files (docker-compose.dev.yml and docker-compose.e2e.yml) have been stashed away for later use in ttat/old-compose-files/.
• Dockerfile.base has been cleaned out, and now serves as the base image for domain-model as well as schema.