RehashAfterJoinWithPreloadTest cleanup
State transfer code cleanup

* Rename StateTransferManager.notifyEndOfTopologyUpdate() to notifyEndOfRebalance() to reflect its actual purpose
* Remove unused method StateTransferManager.isLocalNodeFirst()
* Clarify javadoc LoLocalTopologyManager.confirmRebalance()
ISPN-2589 NPE in InvalidateL1Command

This NPE can appear in both DIST and REPL mode when we process a topology update in which the current node is not a member.

* There is no reason to invalidate segments if we are not a member, so the call to StateConsumerImpl.invalidateSegments() is guarded with a membership check. This also avoids the NPE.
* StateConsumerImpl.invalidateSegments() was wrongly using CommandsFactory.buildInvalidateFromL1Command where it should actually be buildInvalidateCommand()
* Extract all the logic to restart broken transfers from failed sources into a separate method (StateConsumerImpl.restartBrokenTransfers())
* Rename StateConsumerImpl.notifyEndOfTopologyUpdate() to notifyEndOfRebalanceIfNeeded() to clarify its purpose
* Remove StateConsumerImpl.activeTopologyUpdates member as all the logic regarding it has long become redundant
* Remove one of the overloaded variants of CommandsFactory.buildInvalidateFromL1Command that is no longer used