Modify driver for bp add-mysql-support-for-freezer
Modify driver for bp add-mysql-support-for-freezer

Modify driver for sqlalchemy.

ref: https://storyboard.openstack.org/#!/story/2004132

Story: #2004132
Task: #27578

Change-Id: I8f5edca2b921ca4c8b12dc7f26ef7eb2c4242fef
Implements: bp add-mysql-support-for-freezer

openstack/freezer-api,openstack/freezer-api,openstack/freezer-api,openstack/freezer-api