[dd4hep] variant and run env updates (#16524)
[dd4hep] variant and run env updates (#16524)

* [dd4hep] variant and run env updates

* address comments from #16524
LLNL/spack,iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack,iulian787/spack,LLNL/spack,iulian787/spack,LLNL/spack,LLNL/spack