Fix issue when disassociating resources from firewall group

When disassociating ports from firewall group to cleanup resources,
an error is occurred without waiting for the firewall status to complete.

Change-Id: I12a91e75584d5e967d81abab32acf4258995a396
Closes-Bug: #1870296
Signed-off-by: ZijianGuo <guozijn@gmail.com>

neutron_tempest_plugin/fwaas/common/fwaas_v2_client.py

@@ -121,6 +121,11 @@ class FWaaSClientMixin(object):
             firewall_rule_id=firewall_rule_id)
         self._wait_firewall_group_ready(firewall_group_id)
 
+    def update_firewall_group_and_wait(self, firewall_group_id, **kwargs):
+        self.firewall_groups_client.update_firewall_group(
+            firewall_group_id, **kwargs)
+        self._wait_firewall_group_ready(firewall_group_id)
+
     @staticmethod
     def _call_and_ignore_exceptions(exc_list, func, *args, **kwargs):
         """Call the given function and pass if a given exception is raised."""

neutron_tempest_plugin/fwaas/scenario/test_fwaas_v2.py

@@ -299,5 +299,4 @@ class TestFWaaS_v2(base.FWaaSScenarioTest_V2):
             should_connect=False)
 
         # Disassociate ports of this firewall group for cleanup resources
-        self.firewall_groups_client.update_firewall_group(
-            fw_group['id'], ports=[])
+        self.update_firewall_group_and_wait(fw_group['id'], ports=[])