This change is to fix stack already exists issue in the
environment where overcloud with same name is already
deployed. get_network_config action is failing and
error message is stack already exists if overcloud is
deployed already.
Change-Id: If917ae93691540b525d9e1eddcf0c0885ccc5f5e
Closes-Bug: #1714471
(cherry picked from commit 3ea3cbd6d3)