Mark "test_live_migration_with_trunk" as unstable

Most probably due to a new OVN version, the subports status of a trunk
port  are always DOWN. We are investigating this issue right now. In
order to unblock the Nova CI, this test is marked as unstable
temporarily.

Related-Bug: #2024160
Change-Id: I01b6a8eb5b0e319205834d0d36b21e3c15e8c9d6
diff --git a/tempest/api/compute/admin/test_live_migration.py b/tempest/api/compute/admin/test_live_migration.py
index f7c0dd9..5f86a1f 100644
--- a/tempest/api/compute/admin/test_live_migration.py
+++ b/tempest/api/compute/admin/test_live_migration.py
@@ -258,6 +258,7 @@
         port = self.ports_client.show_port(port_id)['port']
         return port['status'] == 'ACTIVE'
 
+    @decorators.unstable_test(bug='2024160')
     @decorators.attr(type='multinode')
     @decorators.idempotent_id('0022c12e-a482-42b0-be2d-396b5f0cffe3')
     @utils.requires_ext(service='network', extension='trunk')