The Backend class in ovsdbapp was modified when adding index
support. Different projects wanted different scopes for their
ovsdb_connections, and this was moved to a property in ovsdbapp.
For now, we can just set ovsdb_connection = None on the backend
class to get the behavior we desire.
Also mocks out autocreate_indicies for a unit test.
Change-Id: I7741a441a55e67354bc0887e5db2f8137073b5b4
28c311ccd7