region support for cinder tests is missing

[Hauke Bruno]

While trying to run some cinder tasks against a multi region setup, it seems that Rally currently doesn't use/fill 'region_name'.

'rally deployment config' point out the correct region name, but while running cinder tasks another region is used (I guess because that endpoint is the first in the list keystone serves).

Simply adding 'region_name=self.credential.region_name,' to the cinder initialization doesn't make a difference, but hard coding the correct region name in https://github.com/openstack/rally/blob/master/rally/osclients.py#L196 works.

[Roman Vasilets (rvasilets)]

Could you try it on master for now(we have merged some patch https://review.openstack.org/#/c/320056/33)? Please show full logs with traceback where region_name related error occurs