The problem is that watcher is passing limit=-1 to novaclient when
listing servers which will always make at least two API calls to be
sure it's done paging:
https://github.com/openstack/python-novaclient/blob/13.0.1/novaclient/v2/servers.py#L896
If we can determine before we list servers that there are only a
certain number where the number of servers is less than 1000. For
example: 4, we should just pass the limit=len(servers) to novaclient
and avoid the second call for paging which takes extra time and
yields no results.
Change-Id: I797ad934a0f8496dbcbf65798e28b0443f238137
Closes-Bug: #1834679
(cherry picked from commit 1e8b17ac46)