Avoid variables overwrite by keystone default config
Avoid variables overwrite by keystone default config

Keystone would overwrite deployment variables
project_domain and user_domain variables with "default"

To avoid that DEFAULT_CONFIG is instantiated in
the __init__ method now

Closes-Bug: 1634474

Change-Id: Ib81298223f31a68d9f79e267654dc35eba58cb95

openstack/rally,openstack/rally,yeming233/rally,openstack/rally,yeming233/rally,openstack/rally