Add a key4hep-sim-reco environment and build it in an image

[tmadlener]

BEGINRELEASENOTES

• Add a key4hep-sim-reco environment that skips building all generators and most of the machine learning adjacent tools
• Add a CI workflow that builds this environment into an ubuntu24 based image

ENDRELEASENOTES

• Includes Make key4hep-stack have more fine-grained variants #791
• Includes Fix a few packages to make them buildable on several tags #793
• Includes Avoid accidentally leaking tokens into the images #792
• Make sim-reco image depend on dev-externals image in one workflow (currently not done for quicker turnaround on development)
• Check whether dev-externals packages are properly re-used here to avoid having duplicated packages in the image
• Check ifthe whole image can be built within the 6 hours we have from github -> They cannot without at least parts of it being available from a buildcache.
• Includes some parts of Changes for the new nightlies #795
• Remove the arm build for now, as that will probably take some time to fix, since at least one package is not compatible with arm: see also simsipm: Add conflict for aarch64 spack/spack-packages#1714

ARM image for sim-reco is not working because simsipm relies on x86 intrinsice (at least on header), see e.g.: https://github.com/key4hep/key4hep-spack/actions/runs/17981415816/job/51148208590#step:8:1742