ENG-5021: enable reverse scan to optimize query with prefix filters and explicit DESC order.
ENG-5021: add junit tests.
Merge branch 'master' into ENG-5021
ENG-5021: remove unnecessary insert procedure in TestOrderBySuite.
ENG-5021: minor fix for one junit test.
Merge pull request #692 from VoltDB/ENG-5021

ENG-5021: enable reverse scan to optimize query with prefix filters and ...