[23.0] Fix rank calculation for jobs waiting to be run by anonymous users

[jdavcs]

As per discussion on galaxyadmin slack from May 22, 2023:

Issue: some jobs run by anonymous users get lots.
Cause: as per @natefoo:

Ok, I suspect it might be the windowed query. This would treat all anonymous users (user_id is null) as a single user: https://github.com/galaxyproject/galaxy/blob/dev/lib/galaxy/jobs/handler.py#L432

If the number of new state anonymous jobs on a given handler is larger than the window size, the ones past the cutoff would never be seen.
...
Basically we just need that rank function to use user_id if not null or session_id if user_id is null.

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[natefoo]

Thanks a ton @jdavcs!