CCCP config poller does not get closed properly when node is rebalanced out

The SDK uses TCP sockets to monitor the cluster for topology changes (eg rebalance).

However, the poller is not cleaned cleaned up properly when a node is rebalanced out, which leads to SentTimeoutExceptions. Once a node has successfully been rebalanced out, it will close any open TCP sockets, but with the poller still active, it tries to request a new cluster configuration.