Title: Ring Hash LB policy doesn't consider subsets

Description:

I'm using envoy:v1.11.0 and I have to provide an affinity by the header value. Another goal is to divide cluster into subsets to allow testing local nodes with exactly same routes inside cloud cluster.
Ring hash policy works just fine but it completely ignores subset configuration although subset routing starts working after switching to round robin or least request policy.

Let me know if I have missed some parts in the documentation which would give me more details.