Flask/DevOps: Intermittent outages

[cklamann]

Users have observed intermittent outages of the STAGER backend, with the server returning a 504. Users report that these outages started a few weeks ago and weren't observed previously. Anecdotally, it seems that concurrency might be a factor, but we'll probably need additional logging to know more.

[kevinlul]

#955

[kevinlul]

Also somewhat related is #754, if query efficiency is a major contributor