For ENG-5605 always use live rejoin with task log even for blocking rejoin

Now that blocking rejoin is a pro feature we can use the task log and don't need two code paths. We were in trouble anyways because transactions arriving during the blocking rejoin snapshot weren't being handled causing dropped transactions.
Merge pull request #1048 from VoltDB/ENG-5605-2

For ENG-5605 always use live rejoin with task log even for blocking rejo...