The overload-drop.zeek and overload-no-drop.zeek tests have proxy,
worker-1 and worker-2 publish to the manager topic. For the drop
case, we verify that both, the senders, but also the manager drops
events. For the no-drop test, the HWMs are set such that all events
are buffered.
The overload-worker-proxy-topic*.zeek tests are similar, but instead
of publishing to the manager topic, proxy, worker-1 and worker-2 publish
to the proxy and worker topics to overload each other. This had
previously resulted in lockups and these tests verify that this doesn't
happen anymore.
