When the InterruptionFrame does not complete within the timeout the
caller was stuck in an infinite loop logging warnings. Now the event
is set after the first timeout so the processor can continue.
Also adds a keyword timeout parameter so callers can customize the
wait duration.
Add tests for the event-based interruption completion: complete() sets
the event, complete() is safe without an event, the event fires at
the pipeline sink, and a warning is logged when the frame is blocked.
Also remove the unconditional await after the timeout so the function
returns instead of hanging when complete() is never called.
