[SLURM] [AI Cluster] configuration change

[Phil Kauffman]

I changed the following configuration options on the AI Cluster in an 
attempt to ensure that the Age factor does not dominate the fairshare value.

- reduced `PriorityWeightAge` 100000 -> 10.
- PriorityDecayHalfLife: 8 hours -> 7 days (Slurm default).

These settings are being tested, so please provide feedback if you feel 
this change made things worse.

Phil


-- 
Phil Kauffman
Systems Admin
Dept. of Computer Science
University of Chicago
kauffman at cs.uchicago.edu