Enable Kafka Event Listener to also send SplitCompletedEvents

[domnikl]

We currently maintain our own Kafka Event Listener that sinks QueryCreated, QueryCompleted and SplitCompleted events in Kafka for further processing. We'd like to switch to the default Kafka event listener included but the missing SplitCompleted events prevents us from doing so currently.

I'll have a look at implementing this and keep the current default of only sending query events as I suppose not everyone needs that.