[pagination tests] Do not fail on zero resources

Since the tests running in parallel, when resources
are deleted by concurrent tests, GET call can return
0 resources, adjust tests to not fail when there are
0 items returned.

This is in continuation of previous patch[1].

[1] https://review.opendev.org/926201

Related-Bug: #2076328
Change-Id: I37c1a3855cb5c37aadec5cda26c89cd3f99e074f
1 file changed