Enable horizon healthcheck

Change-Id: If1c7e2902c2e2ac70965e5718228cc34161ae3d2
Depends-On: https://review.opendev.org/#/c/699005/
Closes-Bug: #1856088
(cherry picked from commit 71b5d40862)

deployment/horizon/horizon-container-puppet.yaml

@@ -265,6 +265,8 @@ outputs:
             net: host
             privileged: false
             restart: always
+            healthcheck:
+              test: /openstack/healthcheck
             volumes:
               list_concat:
                 - {get_attr: [ContainersCommon, volumes]}