[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
diff --git a/neutron_tempest_plugin/api/base.py b/neutron_tempest_plugin/api/base.py
index e260313..e17cf5e 100644
--- a/neutron_tempest_plugin/api/base.py
+++ b/neutron_tempest_plugin/api/base.py
@@ -1544,7 +1544,9 @@
                 pagination_args['marker'] = resources[-1]['id']
             body = self.list_method(**pagination_args)
             resources_ = self._extract_resources(body)
-            self.assertEqual(1, len(resources_))
+            # Empty resource list can be returned when any concurrent
+            # tests delete them
+            self.assertGreaterEqual(1, len(resources_))
             resources.extend(resources_)
         return self._test_resources(resources)
 
@@ -1569,7 +1571,9 @@
                 self.plural_name, uri
             )
             resources_ = self._extract_resources(body)
-            self.assertEqual(1, len(resources_))
+            # Empty resource list can be returned when any concurrent
+            # tests delete them
+            self.assertGreaterEqual(1, len(resources_))
             resources.extend(self._test_resources(resources_))
 
         # The last element is empty and does not contain 'next' link
@@ -1587,7 +1591,9 @@
                 self.plural_name, uri
             )
             resources_ = self._extract_resources(body)
-            self.assertEqual(1, len(resources_))
+            # Empty resource list can be returned when any concurrent
+            # tests delete them
+            self.assertGreaterEqual(1, len(resources_))
             resources2.extend(self._test_resources(resources_))
 
         self.assertSameOrder(resources, reversed(resources2))