ENG-4985: Revert "ENG-4800: Remove unused task log from join producer."

This reverts commit d670d9a515c0e532c45387af85ed6bc7208255ba.
ENG-4985: Make replicated table data transfer during join non-blocking.
Merge pull request #914 from VoltDB/ENG-4985

ENG-4985: Make replicated table data transfer non-blocking during join