Add assert for haproxy service

Due to haproxy service could not start
This assert help to find if that haproxy service is not running
Recommendation of Bz#2133743, c1

Change-Id: Ie0001642b80ba92ff0152546490b48e8190f5b03

tobiko/tests/faults/neutron/test_agents.py

@@ -504,6 +504,7 @@ class L3AgentTest(BaseAgentTest):
     def test_metadata_haproxy_during_stop_L3_agent(self):
         self.agents = neutron.list_l3_agent_hosting_routers(self.router_id)
         pids = self.get_cmd_pids("haproxy", self.router_id)
+        self.assertNotEqual(len(pids), 0)
         self.stop_agent()
 
         # Now check if haproxy processes are still run and have got same pids