ENG-16346: Allow partition list to update safely
ENG-16346: Allow partition list to update safely

Allow InvocationDispatcher.updatePartitionInformation() to be called by anybody
in a thread safe manor. updatePartitionInformation needs to be called during an
elastic operation so new partitions are used and removed partitions are not
used.

VoltDB/voltdb,VoltDB/voltdb,VoltDB/voltdb,VoltDB/voltdb,VoltDB/voltdb,VoltDB/voltdb,VoltDB/voltdb