Ensure that experiment container builds can also work locally

[rdnfn]

Problem

When defaulting to buildx there can be issues with accessing the different build stages. Thus, in the current dev version, only builds via a container registry (e.g. GHCR, Docker hub) work.

Potential Solution

Enable running the build pipeline w/o buildx, or figure out how the local image files can be passed (e.g. by using different docker .