Update some cases of iterating stack resources

Since https://review.openstack.org/#/c/49879 iterating over a
stack will return resource names instead of resources.

This change updates some cases of iterating on a stack, there
are likely others which remaint to be updated.

Change-Id: I3fff5d7d7fd0016d741151010d0e1ce969da01b3
Partial-Bug: #1236678
Merge "Update some cases of iterating stack resources"