Use response_headers_to_add for Envoy-generated error responses

On events like a request timeout, Envoy sends a locally generated response (the `sendLocalReply` function). But it doesn't use the `response_headers_to_add` config option. Which could be useful when `response_headers_to_add` has some diagnostic information (e.g. the `%REQ(x-request-id)%` which was added in #8683)

We can fix this by adding `finalizeResponseHeaders` calls before `sendLocalReply` calls, in functions like `onUpstreamAbort`.