KNL-1224 removing the use of the notification cache entirely, it actually didn't make sense to have it, it would have increased the load on the system in 3 areas (mem, cpu, DB) instead of helping

git-svn-id: https://source.sakaiproject.org/svn/kernel/trunk@307918 66ffb92e-73f9-0310-93c1-f5514f145a0a