re-organize and align docker references

[gannebamm]

As part of #30

The docker container registry re-organisation and the concept of blueprinting is now upstreamed. The thuenen_atlas repo should be aligned with the latest docker-blueprint and the docker containers switched to the official ones like done in this commit: GeoNodeUserGroup-DE/geonode-blueprint-docker@c6a3979

[ridoo]

Versions used in the thuenen_4.x branch:

GEONODE_BASE_IMAGE_VERSION="4.x"
NGINX_BASE_IMAGE_VERSION="1.25.3-latest"
GEOSERVER_BASE_IMAGE_VERSION="2.24.2-latest"
GEOSERVER_DATA_BASE_IMAGE_VERSION="2.24.2-latest"
POSTGRES_BASE_IMAGE_VERSION="15.3-latest"

Custom GeoNode version is accessible via docker hub. All other images are upstream images.