Job scratch (home) directories should be completely clean

[alahiff]

Currently there are some HTCondor files visible as well as a PROMINENCE log and json file. This stuff shouldn't be visible to users, especially with prominence exec being available.

Checks:

• [x] Singularity jobs run successfully
• [x] udocker jobs run successfully
• [x] Input files work
• [x] Artifacts work
• [ ] Output file uploads work
• [ ] Output directory uploads work
• [ ] Singularity multi-node MPI jobs work
• [ ] udocker multi-node MPI jobs work