Migration tests in v2.6 should not repeat all migration tests.

Now LiveMigrationRemoteConsolesV26Test inherits from
LiveMigrationTest, which will unnecessarily repeat all tests in
LiveMigrationTest. This is to change the v26 class inheritance
to save the running time.

Change-Id: I0929ad8a5ad5f1a4c2ae2d917e001c26aa9cec66
diff --git a/tempest/api/compute/admin/test_live_migration.py b/tempest/api/compute/admin/test_live_migration.py
index 8350f7c..5a60dc6 100644
--- a/tempest/api/compute/admin/test_live_migration.py
+++ b/tempest/api/compute/admin/test_live_migration.py
@@ -29,13 +29,11 @@
 LOG = logging.getLogger(__name__)
 
 
-class LiveMigrationTest(base.BaseV2ComputeAdminTest):
-    max_microversion = '2.24'
-    block_migration = None
+class LiveMigrationTestBase(base.BaseV2ComputeAdminTest):
 
     @classmethod
     def skip_checks(cls):
-        super(LiveMigrationTest, cls).skip_checks()
+        super(LiveMigrationTestBase, cls).skip_checks()
 
         if not CONF.compute_feature_enabled.live_migration:
             skip_msg = ("%s skipped as live-migration is "
@@ -55,11 +53,11 @@
         # TODO(mriedem): SSH validation before and after the instance is
         # live migrated would be a nice test wrinkle addition.
         cls.set_network_resources(network=True, subnet=True)
-        super(LiveMigrationTest, cls).setup_credentials()
+        super(LiveMigrationTestBase, cls).setup_credentials()
 
     @classmethod
     def setup_clients(cls):
-        super(LiveMigrationTest, cls).setup_clients()
+        super(LiveMigrationTestBase, cls).setup_clients()
         cls.admin_migration_client = cls.os_admin.migrations_client
 
     def _migrate_server_to(self, server_id, dest_host, volume_backed=False):
@@ -91,6 +89,11 @@
         self.assertEqual(target_host, self.get_host_for_server(server_id),
                          msg)
 
+
+class LiveMigrationTest(LiveMigrationTestBase):
+    max_microversion = '2.24'
+    block_migration = None
+
     def _test_live_migration(self, state='ACTIVE', volume_backed=False):
         """Tests live migration between two hosts.
 
@@ -168,7 +171,7 @@
         self.assertEqual(volume_id1, volume_id2)
 
 
-class LiveMigrationRemoteConsolesV26Test(LiveMigrationTest):
+class LiveMigrationRemoteConsolesV26Test(LiveMigrationTestBase):
     min_microversion = '2.6'
     max_microversion = 'latest'