Update dis

Update the CI scripts for the DIS stub to be consistent with the more generic DVMP scripts. Also did some more restructuring of the benchmark to make it easier to split off a generic benchmark library in the future.

benchmarks/dis/config.yml

 dis:generate:
   stage: initialize
-  image: eicweb.phy.anl.gov:4567/eic/juggler/juggler:latest
   needs: []
   timeout: 1 hours
   artifacts:
     paths:
       - results
   script:
-    - bash dis/gen.sh
+    - bash benchmarks/dis/gen.sh
 
 dis:process:
   stage: process