Only include a scheduled rule if it is strictly before the end time

The exact moment of the end time is the end of the schedule. We do not want to include a rule when filter_configure_sync wakes up at 00:15:00 etc and is on a not-slow system that processes this code during the interval 00:15:00 to 00:15:01. This should help intermittent issues with schedules not finishing at the appropriate 15-minute boundary. Might help or fix #3558
Merge pull request #1239 from phil-davis/patch-9