os-client-config can work for standalone mode with specifically written
clouds.yaml file providing auth_type as None.
This patch changes `bifrost-keystone-client-config` role to write
`clouds.yaml` file also when keystone is not installed, with a `bifrost`
cloud configured, so that users can write automation scripts
around ironic installed by bifrost in unified manner independently of
whether keystone is installed or not, by using
openstack --os-cloud bifrost ...
command.
This effectively mimics current `env-vars` file in bifrost, but using
`clouds.yaml` configuration file.
Change-Id: I4c27ffed20b3d02723f7be99ccd61d8cee74bea1
de0a964e1a