customer call follow-up issues

Created by: keegancsmith

This issue is to track the follow-up work after a customer call from https://github.com/sourcegraph/customer/issues/977

Just filing one big issue for convenience. Some may split off into own issues.

• metric src_search_requests_total is lieing
• resource estimator lies about indexserver vs webserver. Says they need 4 zoekt-webserver and 2 zoekt-sourcegraph-indexserver. This confused and wasted a bunch of time.
• wants to make an slo by search type. need to get back and share the metrics for them to use.
• the time taken for a search was different to what user experiences. I've seen this myself.