Major Description
TestChoreService has been seen timing out in recent builds and the timeouts seem to be rooted in how the ChoreService cancels its chores when being shutdown. The issue is that during shutdown, the ChoreService calls synchronized methods on the ScheduledChore which could cause indefinite blocking if the scheduled chore is hanging in a synchronized method. We should instead call the appropriate cancel method within the ChoreService and add logic into ScheduledChores that allows them to realize when they have been cancelled.