Fix issue where caching leads to DVMP samples to not be re-generated when the requested number of events changes.

Add benchmark/exception headers as symlink to the benchmarks for now, in the future these should be moved to the util library

disabled debug logging for now, will re-enable after having established that running many jobs works

Got rid of fname script for dvmp, and split up generator artifacts from reconstruction artifacts (input versus results directories

 - 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...

- Currently throwing (central) electrons.
- This will be replace with pythia8 input file.
  This should be added to the TODO list