Fix KafkaBolt test failure: tick tuple should not be acked

From STORM-2387, I changed KafkaBolt to make sure it doesn't ack tick tuples.
(Tick tuples are generated from each executor and don't trigger ACK_INIT so actually it should not be acked. Acker will keep them and remove some for message timeout so not a big deal though.)

But I forgot to fix unit test for that, and also missed to check test result. This issue is for making quick fix for that.