Remove explicit adding QoS policy  to the cleianup

The _create_qos_policy method mistakenly added the policy object
to the cleanup, whereas delete_qos_policy expects a policy_id

But in next steps qos_policy is correctly deleted by
BaseNetworkTest.cleanup_resources

Change-Id: If35d7e5dd14a508085dde4e719f6f1e4386d8e66
diff --git a/neutron_tempest_plugin/scenario/test_qos.py b/neutron_tempest_plugin/scenario/test_qos.py
index 74be216..12c862f 100644
--- a/neutron_tempest_plugin/scenario/test_qos.py
+++ b/neutron_tempest_plugin/scenario/test_qos.py
@@ -20,6 +20,7 @@
 from oslo_log import log as logging
 from tempest.common import utils as tutils
 from tempest.common import waiters
+from tempest.lib.common.utils import data_utils
 from tempest.lib.common.utils import test_utils
 from tempest.lib import decorators
 
@@ -134,13 +135,12 @@
                                    self.security_groups[-1]['id'])
 
     def _create_qos_policy(self):
+        name = data_utils.rand_name('test-policy')
         policy = self.os_admin.network_client.create_qos_policy(
-                                        name='test-policy',
+                                        name=name,
                                         description='test-qos-policy',
                                         shared=True)
         self.qos_policies.append(policy['policy'])
-        self.addCleanup(test_utils.call_and_ignore_notfound_exc,
-            self.os_admin.network_client.delete_qos_policy, policy)
         return policy['policy']['id']
 
     def _create_qos_bw_limit_rule(self, policy_id, rule_data):