Function finish_task 

pub async fn finish_task<T>(
    slot: &mut TaskSlot<T>,
    graceful_timeout: Duration,
    abort_timeout: Duration,
) -> Option<TaskJoinOutcome<T>>

Gracefully joins one task, then aborts and joins it within a second bound.

This preserves typed task results. The handle and forced-abort state remain in slot while the function is pending, so canceling the finish future cannot detach the task or lose its expected cancellation provenance. A terminal join clears the slot, while a second timeout leaves the incomplete task in place for another drain attempt.