CHG optimize the autograde calculation caching

[wabscale]

We can and should be more intelligent about how we handle the autograde calculations. We know they can only changed for a student when new submissions are processed. Knowing this, we can potentially cache the results for much longer (say like a week or two) and clear the cached results when the submissions is processed.

From the flask-caching docs

user_has_membership('demo', 'admin')
user_has_membership('demo', 'user')

cache.delete_memoized(user_has_membership, 'demo', 'user')

[github-actions]

Issue is stale