Cleaned up and simplified the config/env.sh and util/build.sh

• We should limit the number of new environment variables. They increase complexity which should be mostly absorbed by using containers.
• Any new environment variables should be set via the ci yml file or defined the UI. https://docs.gitlab.com/ee/ci/variables/README.html#custom-environment-variables
• Removed dummy scripts
• Removed dvmp dummy jobs.
• Fixed dvmp output data. Note the out artifacts should go in results/dvmp if they are in the dvmp directory. This will just make things easier later on for collecting and summarizing results.
• updated dvmp/scripts/run_generator_instance.sh
• Added dvmp.sh to run geant4/reconstruction. Note dvmp/dvmp.sh could be named something more specific, like dvmp/dvmp_barrel_decays.sh depending on the input, analysis, etc...