xds-k8s driver: remove "Client subchannel must have no sockets" check (#25460)

tools/run_tests/xds_k8s_test_driver/framework/test_app/client_app.py

@@ -160,7 +160,8 @@ class XdsTestClient(framework.rpc.grpc.GrpcApp):
                     try:
                         subchannel = self.find_subchannel_with_state(
                             channel, state, **rpc_params)
-                        logger.info('Found subchannel in state %s: %s', state,
+                        logger.info('Found subchannel in state %s: %s',
+                                    _ChannelzChannelState.Name(state),
                                     subchannel)
                     except self.NotFound as e:
                         # Otherwise, keep searching.

tools/run_tests/xds_k8s_test_driver/framework/xds_k8s_testcase.py

@@ -457,9 +457,6 @@ class SecurityXdsKubernetesTestCase(XdsKubernetesTestCase):
                        1,
                        msg="Client channel must have exactly one subchannel "
                        "in state TRANSIENT_FAILURE.")
-        sockets = list(
-            test_client.channelz.list_subchannels_sockets(subchannels[0]))
-        self.assertEmpty(sockets, msg="Client subchannel must have no sockets")
 
     @staticmethod
     def getConnectedSockets(