ISPN-2897 NPE in DefaultConsistentHash

If any partition is rebalancing during a merge, the merge coordinator
should end the rebalance it and start a new one with all the members.
Enabling tests that were disabled due to ISPN-2106 (no longer relevant on 5.2 and tests seem to work)
ISPN-2777 ReplicatedConsistentHash.isKeyLocalToNode(node, key) should return false if the node is not a member yet

* Also added some sanity checks to detect illegal usage.
* Fix incomplete transport mocking in PutForExternalReadTest.testExceptionSuppression and resolve some generics related compiler warnings.
ISPN-2757 ReplaceCommand in REPL mode cluster does not perform any modifications if the entry was not yet transfered during rehashing

ReplicationInterceptor needs to be smart an if the command is conditional but the affected value is not yet available locally because state transfer did not have the chance to fetch it yet then we should fetch it now.
Refactor BaseDistributionInterceptor.needsRemoteGet to make it more readable

Improve logging and asserts in BaseDistStateTransferConsistencyTest to make it easier to see on which of the caches we have unexpected results.
wip