Add option to disable healthcheck for storagedriver in registry
From https://forum.gitlab.com/t/docker-registry-not-available/8049
It seems that registry generates 503 responses when the storage healthcheck fails, and the healthcheck fails when it is configured with an s3 backend that is empty.
Disabling the healthcheck is a workaround until #3381 is done.
Related to !2429 (merged)