Cleanup images properly
Cleanup images properly

Images weren't deleted properly due to bad request sent to
glance API. Also ImageService ignored 'next' parameter returned from
glance API when listing images which is required when more images
are present.

The fix lists all images properly. If 'next' parameter is present
in the glance API response then the API is asked to send next part
of image list.

Closes-Bug: 1866988
Change-Id: I9ebeccb545576e43ef0fc96c29169ae16f261f34

openstack/tempest,cisco-openstack/tempest,openstack/tempest,cisco-openstack/tempest