R1:69538274c1ac

Garbage collect old daemon records based on modification date, not creation date

Summary:
Fixes T12720. Currently, old daemon records are collected based on creation date. By default, the GC collects them after 7 days.

After T12298, this can incorrectly collect hibernating daemons which are in state "wait".

In all cases, this could fail to collect daemons which are stuck in "running" for a long time for some reason. This doesn't seem to be causing any problems right now, but it makes me hesitant to do…