Expand war files before or in Docker Build

[artntek]

A good discussion with @vchendrix helped me understand that it's better to have the metacat war file already exploded as part of the docker build (or the build.sh stage before that), instead of doing it in the entrypoint script.

This then allows the use of configMaps in the helm chart, to override the configuration directly, instead of doing search-and-replace in files etc. (For example, some of the replacement stuff we do in docker-entrypoint.sh)