xds interop: resume failover tests on all branches (#30344)

Resume the failover test on all branches, now that the following PRs were backported to all branches:

- grpc/grpc-go#5508
- grpc/grpc-java#9389

Continues #30308
ref b/238226704

tools/run_tests/xds_k8s_test_driver/tests/failover_test.py

@@ -18,7 +18,6 @@
 from absl.testing import absltest
 
 from framework import xds_k8s_testcase
-from framework.helpers import skips
 from framework.infrastructure import k8s
 from framework.test_app import server_app
 
@@ -34,12 +33,6 @@ class FailoverTest(xds_k8s_testcase.RegularXdsKubernetesTestCase):
     REPLICA_COUNT = 3
     MAX_RATE_PER_ENDPOINT = 100
 
-    @staticmethod
-    def is_supported(config: skips.TestConfig) -> bool:
-        # TODO(b/238226704): Remove when the fix for selecting correct
-        #  cluster is backported.
-        return config.version_gte('master')
-
     def setUp(self):
         super().setUp()
         self.secondary_server_runner = server_app.KubernetesServerRunner(