SAK-23244 Have an index on eventTime so as don't do full table scan.

All displays of scheduler_trigger_events sort by the time of the event. So although the index doesn't help once you have large offsets into the index it does make the initial loads much faster. Hibernate index creation seems to be broken so we manually create the index from a .sql file.

git-svn-id: https://source.sakaiproject.org/svn/jobscheduler/trunk@120223 66ffb92e-73f9-0310-93c1-f5514f145a0a