Refactor test cases after adding new params to create_floatingip.

Change-Id: I1feaed67e46edce85397907528e23c4a5f487c1f
diff --git a/neutron_tempest_plugin/scenario/test_trunk.py b/neutron_tempest_plugin/scenario/test_trunk.py
index 9a92b38..e6d8863 100644
--- a/neutron_tempest_plugin/scenario/test_trunk.py
+++ b/neutron_tempest_plugin/scenario/test_trunk.py
@@ -65,7 +65,7 @@
                 'server': server}
 
     def _create_server_with_fip(self, port_id, **server_kwargs):
-        fip = self.create_and_associate_floatingip(port_id)
+        fip = self.create_floatingip(port_id=port_id)
         return (
             self.create_server(
                 flavor_ref=CONF.compute.flavor_ref,