Remove default=None when set value in config
Remove default=None when set value in config

By default oslo.cfg sets the default values as None.
Thus, there is no need to explicitly do this.

Trivial-Fix

Change-Id: I5b822021a1fe83be3755791278df6b4f498e6fef

mahak/keystone,ilay09/keystone,openstack/keystone,mahak/keystone,openstack/keystone,ilay09/keystone,rajalokan/keystone,mahak/keystone,ilay09/keystone,rajalokan/keystone,openstack/keystone,rajalokan/keystone