Skip test_server_connectivity_cold_migration_revert until fixed
Skip test_server_connectivity_cold_migration_revert until fixed

We're having a hard time landing changes like
https://review.openstack.org/#/c/601830/ due to
persistent intermittently failing tests that are
not getting attention to resolve, so this skips
one of those tests until the bug is fixed.

Change-Id: I7c2080acbcd47b9fb1deefd30d427f3e4076ea39
Related-Bug: #1788403

cisco-openstack/tempest,cisco-openstack/tempest,openstack/tempest,masayukig/tempest,masayukig/tempest,openstack/tempest