Bug: Superset permissions cached indefinitely

[bmtcril]

The security manager uses an LRU cache on LMS calls to get a user's courses, on a small site it may never expire leading to old permisisons such as not being able to log in to Superset or having instructor access when it has been revoked: https://github.com/openedx/tutor-contrib-aspects/blob/90a8afd161b4664352a3553b919a73a5ad8a4b98/tutoraspects/templates/aspects/apps/superset/pythonpath/openedx_sso_security_manager.py#L193C1-L194

We should either make this a time based cache or remove it altogether.

[bmtcril]

We're seeing reports of this on the beta server again, even though I've confirmed it's got the fix for the LRU cache, so I'm going to reopen it. Waiting to hear if bouncing the server fixes it like it did last time. So far it's persisted over an hour without getting new permissions.