Enhancement: Make init try loop optional via envvar setting

[jspaleta]

init loop is great for single backend using embedded etcd.
For more complicated situations with multiple backends or external etcd, it might be good to give users the ability to disable the init loop logic so they can explicitly handle init via a means they control.

For example in k8s, an explicit initcontainer might be best for a statefulset configuration.

Implementation Proposal

have new envvar in entrypoint.sh DISABLE_BACKEND_INIT, if set skip the init wait loop logic entirely.