ENG-7068 database fails if security is enabled with no users
ENG-7068 removed failing redundant test
ENG-7068 restored removed test (modified to not fail)
ENG-7068 code review changes
ENG-7068 more code review changes
ENG-7068 removed unnecessary test
Merge pull request #1760 from VoltDB/ENG-7068

ENG-7068 database fails if security is enabled with no users