We have stable/wallaby branch as latest stable and d-g test only latest stable branch to make sure the compatibility of legacy jobs. Hope this is last stable we need to update/support in d-g. This commit moves the legacy stable job testing to stable/wallaby. Depends-On: https://review.opendev.org/c/openstack/devstack/+/784974 Change-Id: I5542dca0f8050a6e21aff773f49eb4799ec26828