JGroups VERIFY_SUSPECT can kick a live node soon after it re-joins

If a protocol considers a cluster node dead, the protocol sends a SUSPECT message. The VERIFY_PROTOCOL then pings the node to verify that the node is unresponsive. If the node does not respond before the VERIFY_SUSPECT time-out period elapses, the node is kicked from the cluster. Previously, after a cluster member was kicked and then rejoined the cluster, the member could be kicked again if it joined the cluster before the time-out period had elapsed. This happened because the member was not removed from the list of the suspected members after it has left the cluster. Now, a node that leaves the cluster is removed from the list of suspected members so that the member is not kicked after rejoining the cluster again even if it rejoins the cluster before the timer expires.