Remove "sqlite_clean_db" option
Remove "sqlite_clean_db" option

This only affects unit tests and is not likely
to be configured by anyone.

Just remove the option to simplify and clean up
a bit.

Change-Id: I6baf8e3aeb08d28568079457cd900acbe7c63c5d

Nexenta/cinder,bswartz/cinder,cloudbase/cinder,Hybrid-Cloud/cinder,openstack/cinder,phenoxim/cinder,j-griffith/cinder,eharney/cinder,openstack/cinder,phenoxim/cinder,eharney/cinder,Nexenta/cinder,Datera/cinder,NetApp/cinder,mahak/cinder,mahak/cinder,bswartz/cinder,Hybrid-Cloud/cinder,cloudbase/cinder,Datera/cinder,j-griffith/cinder,ge0rgi/cinder,NetApp/cinder