Avoid swaping back in test_volume_swap

starting with Epoxy/libvirt 10, for iSCSI devices
the second swap breaks with
```
Volume rebase failed: Requested operation is not valid:
Setting different DAC user or group on /dev/sda which is already in use
```

The swap back is very much synthetic anyway, IRL this api is
not meant for user interactions and is mainly used by cinder's
non-driver assisted volume migration, which never does that swap back.

Related-Issue: PRODX-52879
Change-Id: I4871da31441d9bb7c5da62cb25aca897839d68cf
diff --git a/tempest/api/compute/admin/test_volume_swap.py b/tempest/api/compute/admin/test_volume_swap.py
index dcdfae2..2e22baf 100644
--- a/tempest/api/compute/admin/test_volume_swap.py
+++ b/tempest/api/compute/admin/test_volume_swap.py
@@ -119,9 +119,6 @@
         5. Swap volume from "volume1" to "volume2" as admin.
         6. Check the swap volume is successful and "volume2"
            is attached to "instance1" and "volume1" is in available state.
-        7. Swap volume from "volume2" to "volume1" as admin.
-        8. Check the swap volume is successful and "volume1"
-           is attached to "instance1" and "volume2" is in available state.
         """
         # Create two volumes.
         # NOTE(gmann): Volumes are created before server creation so that
@@ -157,21 +154,6 @@
         self.assertEqual(1, len(vol_attachments))
         self.assertIn(volume2['id'], vol_attachments[0]['volumeId'])
 
-        # Swap volume from "volume2" to "volume1"
-        self.admin_servers_client.update_attached_volume(
-            server['id'], volume2['id'], volumeId=volume1['id'])
-        waiters.wait_for_volume_resource_status(self.volumes_client,
-                                                volume2['id'], 'available')
-        waiters.wait_for_volume_resource_status(self.volumes_client,
-                                                volume1['id'], 'in-use')
-        self.wait_for_server_volume_swap(server['id'], volume2['id'],
-                                         volume1['id'])
-        # Verify "volume1" is attached to the server
-        vol_attachments = self.servers_client.list_volume_attachments(
-            server['id'])['volumeAttachments']
-        self.assertEqual(1, len(vol_attachments))
-        self.assertIn(volume1['id'], vol_attachments[0]['volumeId'])
-
 
 class TestMultiAttachVolumeSwap(TestVolumeSwapBase):
     """Test swapping volume attached to multiple servers