Berbican has been historically using own implementation with sqlalchemy
to connect to database but this causes some feature gaps with the other
services using oslo.db to generate database engine.
This replaces the own implementation by oslo.db's one so that barbican
can also leverage the features implemented in the shared library.
With this change the deprecated database options are removed, because
the deprecated options were already removed from oslo.db.
Change-Id: I10fe4ab04996885e8aff7fab8ace78a6fe7eb6e7
2d405a8bfd