Update sample conf for new oslo.db release

oslo.db just released a new version, and it's broken our gate config
check, so update it.

Change-Id: I0d077d0f55fbc2ab9faac5ff9deaadba00452869
Closes-Bug: #1393559
(cherry picked from commit c0f8529dabbf064bb582d5b10e032070f90ccc89)