NSX|P: Fix loadbalancer delete cascade for pools

When the pool is deleted the listeners were already removed.

Change-Id: I742ae44fca3c40fae4b0dc4ad577be57765c59ee

vmware_nsx/services/lbaas/nsx_p/implementation/pool_mgr.py

@@ -240,4 +240,9 @@ class EdgePoolManagerFromDict(base_mgr.NsxpLoadbalancerBaseManager):
         completor(success=True)
 
     def delete_cascade(self, context, pool, completor):
+        # Listeners were already deleted
+        pool['listeners'] = []
+        pool['listener'] = None
+        pool['listener_id'] = None
+
         self.delete(context, pool, completor)

vmware_nsx/tests/unit/services/lbaas/test_nsxp_driver.py

@@ -1337,6 +1337,18 @@ class TestEdgeLbaasV2Pool(BaseTestEdgeLbaasV2):
             self.assertTrue(self.last_completor_called)
             self.assertTrue(self.last_completor_succees)
 
+    def test_delete_cascade(self):
+        self.reset_completor()
+        with mock.patch.object(self.pool_client, 'delete'
+                               ) as mock_delete_pool:
+            self.edge_driver.pool.delete_cascade(
+                self.context, self.pool_dict,
+                self.completor)
+
+            mock_delete_pool.assert_called_with(LB_POOL_ID)
+            self.assertTrue(self.last_completor_called)
+            self.assertTrue(self.last_completor_succees)
+
     def test_delete_with_persistency(self):
         with mock.patch.object(self.vs_client, 'get'
                                ) as mock_vs_get, \