[sfc] Remove unused floating ip methods

As tempest.scenario.manager was announced stable interface in Tempest
27.0.0[1] it can be now reused in plugins.

Removed methods:
    * _associate_floating_ip
    * _disassociate_floating_ip

Etherpad concerning this effort:
https://etherpad.opendev.org/p/tempest-scenario-manager-cleanup

[1] https://docs.openstack.org/releasenotes/tempest/v27.0.0.html#release-notes-27-0-0

Change-Id: I317ef8253c61594aefb6def55e739dd7c5040fc1
diff --git a/neutron_tempest_plugin/sfc/tests/scenario/manager.py b/neutron_tempest_plugin/sfc/tests/scenario/manager.py
index e2571ab..fea5d09 100644
--- a/neutron_tempest_plugin/sfc/tests/scenario/manager.py
+++ b/neutron_tempest_plugin/sfc/tests/scenario/manager.py
@@ -28,14 +28,14 @@
 from tempest.lib.common.utils import data_utils
 from tempest.lib.common.utils import test_utils
 from tempest.lib import exceptions as lib_exc
-import tempest.test
+from tempest.scenario import manager
 
 CONF = config.CONF
 
 LOG = log.getLogger(__name__)
 
 
-class ScenarioTest(tempest.test.BaseTestCase):
+class ScenarioTest(manager.NetworkScenarioTest):
     """Base class for scenario tests. Uses tempest own clients. """
 
     credentials = ['primary']
@@ -490,22 +490,6 @@
                         floating_ip['id'])
         return floating_ip
 
-    def _associate_floating_ip(self, floating_ip, server):
-        port_id, _ = self._get_server_port_id_and_ip4(server)
-        kwargs = dict(port_id=port_id)
-        floating_ip = self.floating_ips_client.update_floatingip(
-            floating_ip['id'], **kwargs)['floatingip']
-        self.assertEqual(port_id, floating_ip['port_id'])
-        return floating_ip
-
-    def _disassociate_floating_ip(self, floating_ip):
-        """:param floating_ip: floating_ips_client.create_floatingip"""
-        kwargs = dict(port_id=None)
-        floating_ip = self.floating_ips_client.update_floatingip(
-            floating_ip['id'], **kwargs)['floatingip']
-        self.assertIsNone(floating_ip['port_id'])
-        return floating_ip
-
     def check_floating_ip_status(self, floating_ip, status):
         """Verifies floatingip reaches the given status