Base direct user estimates on responses to directory requests, rather than responses
Relays report two different statistics related to directory requests:
"dirreq-v3-reqs"contain the number of requests broken down by country and
"dirreq-v3-resp"contain the number of responses broken down by status code.
We're using the number of responses to estimate bridge users but the number of requests to estimate direct users. We should use the same input for both estimates. Using the number of responses (successful requests) seems more intuitive, because we're assuming that each client needs to fetch 10 fresh consensuses every day, and they might have to make more than 10 requests if one or more of them is not successful.
I'll attach an analysis shortly.
This minor enhancement came up when working on #18167 (moved).