Check to make sure that when Celery completes a task, that task and its associated data is removed from Redis immediately

[ccostino]

When we discovered that none of the Redis keys were expiring, we started adding expiration dates to the things that need them (and have more to do). That said, it seems there is a lot that is still sitting in Redis that has no need to be once a task is completed by Celery. The task information and any associated data should be cleared out automatically once a task is finished in Celery, but that does not appear to be happening. There's no need to hold on to stuff and wait for it to expire if it's been fully taken care of.

Let's double check that this is indeed the case and make any adjustments necessary if it's not.

Implementation Sketch and Acceptance Criteria

• Read over Celery's Task docs (and any other relevant documentation) to make sure we have a clear understanding of what should happen when a task completes and if we need to explicitly tell it to clear things out of the queue when done
• Make any necessary adjustments to our Celery configuration; note that we have multiple queues to be mindful of!
• Adjust tests as necessary
• Test locally and in staging by getting some tasks to fire off and monitor that they actually go in and out of Redis as expected once completed

Security Considerations

• We should not be holding on to stale data in our Redis cluster when it's not necessary.