Improve heuristic for outhole style troughs with manual plunger

[jabdoa2]

Consider this scenario:

1. A ball drains into the outhole. This triggers an eject of a new ball.
2. Outhole ejects to the trough and trough ejects to the plunger
3. Ball hits the plunger and is instantly plunged (before it settles in the plunger)
4. The trough receives the ball from the drain
5. Ball count in the trough did not change -> It assumes the eject failed
6. The ball from the drain is lost
7. Trough retries the eject and thereby eject a second ball to the playfield

We got an heuristic which assumes that the ball skipped the plunger (did not settle) if it did not return to the previous device. However, this fails here because of the incoming ball from drain. We have to improve the heuristic and add a better test for this kind of troughs.