ENG-6075 clone table elastic state post-truncate
ENG-6075 oops I committed a scratch file
ENG-6075 Make CopyOnWriteTest compile.
ENG-6075 Completely reverting the TRUNCATE TABLE support changes to ElasticIndexReadContext re:nshi
Merge pull request #1276 from VoltDB/ENG-6075-elastic-truncate

Eng 6075 elastic truncate r=nshi