ENG-10444: Synchronize truncate and getSafePointDrId methods so that a different thread will not see inconsistent data while truncate is happening in a drconsumer partition thread.
ENG-10444: Synchronize truncate and getSafePointDrId methods so that
a different thread will not see inconsistent data while truncate
is happening in a drconsumer partition thread.

simonzhangsm/voltdb,simonzhangsm/voltdb,paulmartel/voltdb,migue/voltdb,deerwalk/voltdb,paulmartel/voltdb,VoltDB/voltdb,migue/voltdb,simonzhangsm/voltdb,simonzhangsm/voltdb,deerwalk/voltdb,VoltDB/voltdb,migue/voltdb,simonzhangsm/voltdb,VoltDB/voltdb,deerwalk/voltdb,VoltDB/voltdb,paulmartel/voltdb,deerwalk/voltdb,paulmartel/voltdb,simonzhangsm/voltdb,migue/voltdb,paulmartel/voltdb,VoltDB/voltdb,paulmartel/voltdb,simonzhangsm/voltdb,deerwalk/voltdb,migue/voltdb,deerwalk/voltdb,simonzhangsm/voltdb,migue/voltdb,paulmartel/voltdb,migue/voltdb,deerwalk/voltdb,paulmartel/voltdb,VoltDB/voltdb,deerwalk/voltdb,migue/voltdb,VoltDB/voltdb