Skip PortNotFound when unbinding port

There might be cases when user deleted port before doing vif_detach.
With this patch info message will be shown in the logs for such cases.

Change-Id: Ic3c5073130a4839f27692db1862100bdd7dfca1e
diff --git a/ironic_tempest_plugin/tests/scenario/baremetal_standalone_manager.py b/ironic_tempest_plugin/tests/scenario/baremetal_standalone_manager.py
index 507513b..25fb74e 100644
--- a/ironic_tempest_plugin/tests/scenario/baremetal_standalone_manager.py
+++ b/ironic_tempest_plugin/tests/scenario/baremetal_standalone_manager.py
@@ -330,6 +330,8 @@
     def resource_cleanup(cls):
         cls.cleanup_floating_ip(cls.node_ip)
         vifs = cls.get_node_vifs(cls.node['uuid'])
+        # Remove ports before deleting node, to catch regression for cases
+        # when user did this prior unprovision node.
         for vif in vifs:
             cls.ports_client.delete_port(vif)
         cls.terminate_node(cls.node['uuid'])