A brand new replica in the legacy setup reports healthy before replicating index from its leader

In the legacy mode when you add a brand new replica it immediately starts reporting healthy even if it hasn't fully replicated index from its leader. This issue is also exhibited when you shut down a replica and start it after a lot of data is indexed on the leader.

If the replica reports healthy LB would continue to forward incoming requests to it and this would result in inconsistent data being retuned to the caller.