Don't release tasks held beyond suite stop.

Addresses another of the remaining "TODO ISO" comments.  Tasks are still held beyond the suite stop point, which is handled differently to the end of a recurrence (for which tasks just disappear) because you might want to restart a suite with a later stop time.
Removed this as not relevant.  For tasks with a built-in stop point (this applies to manually inserted tasks that you only want to run a finite number of times, usually once), the task stop point is treated like the end of a recurrence bounds - the task isn't held, it just disappears.