Prior to change Ic9db8d852fbfa50f4ac574ebe524c1fb1d85c588
the tripleoclient constants OVERCLOUD_ROLES_FILE and
OVERCLOUD_NETWORKS_FILE was used as the defaults.
This was changed to use the defaults in process-templates.py
This restores the previous behaviour, honoring the tripleoclient
constants.
Closes-Bug: #1934010
Change-Id: Ie133a6718ca50f30fee7a48fc83ff0e89d84d2dc