Title: Let no-scope queries go through the filter chain when scope not found, currently it sends a 404 via sendLocalReply.

Description:

When no scope found, let's let the filter-chain handle it as a no-route-entry request, and take the right action. By default, this ends w/ Router filter sending back a 503 error (no route entry).

This update will allow some special purpose query (e.g., data-plane Health check queries) pass through the filter chain and gets handled by the filter chain correctly.