Adapt to the renamed events-broker.jar build artifact

With Ie7eb4be2f5a6314f6a0691047a8d1c5883a4b0c0 the build result of the
events-broker was renamed from libevents-broker.jar to
events-broker.jar.

Change-Id: Ia841665c2cd86a59e6015065cbe1e73aff4c5447