Remove the unused coding style modules
Remove the unused coding style modules

Python modules related to coding style checks (listed in blacklist.txt in
openstack/requirements repo) are dropped from lower-constraints.txt
as they are not actually used in tests (other than pep8).

more info: https://github.com/openstack/requirements/blob/master/blacklist.txt

Change-Id: I01944ebdbf6311580f8991da61256e93be6823b3

openstack/oslo.db,openstack/oslo.db