Retrieve the running assessment test sessions after the coach stopped an
assessment mode. The process is slightly delayed.

For large instance, the size of a cluster infos event is quiet large
(1MB) and is sent every second. If these events are queued, it can takes
a lot of RAM. The time limit ensure that such events don't stay in queue
if they are not processed quickly, as they are all the same, one in the
queue is enough.