isRangeEntirelyOwned is a helper to confirm a input range belongs entirely to the caller. However, the helper only checks the range belongs to 1 shards, but does not verify the returned shard is the same as the caller shard.

The goal of this ticket is to extend the method to provide this check.

Note the check must be extended to the unsharded case as well, making sure for the "non-routable" case to be the primary and for the "unsplittable" case to be the data shard.