Add placeholder `identity` flag to `LocalAuxiliaryUnit._launch_job_group`.
Add placeholder `identity` flag to `LocalAuxiliaryUnit._launch_job_group`.

PiperOrigin-RevId: 474018749
Change-Id: I23e5696788764d4b373b6bdfff4e04649179d4d6
GitOrigin-RevId: 0d9d1a8df332734a2a865c769553cf52fb0aadf3

deepmind/xmanager,deepmind/xmanager