add liveness_check endpoint to personas
add liveness_check endpoint to personas

PiperOrigin-RevId: 292371498
Change-Id: I1ff52f094a2e67ba646178c3eed3f4b2a9f12002

GoogleCloudPlatform/healthcare-federated-access-services,GoogleCloudPlatform/healthcare-federated-access-services,GoogleCloudPlatform/healthcare-federated-access-services,GoogleCloudPlatform/healthcare-federated-access-services