This is a silly config option. We only have one database driver in-tree
and no plans to add more (SQLAlchemy is best in class). There's also no
way we'd be able to support out-of-tree drivers. Remove it entirely.
Change-Id: Ica3b2e8fcb079beca652e81d2230bcca82fb49d7
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>