Update webrequest validation job thresholds
(Depends on 1275815: Update webrequest validation algorithm | https://gerrit.wikimedia.org/r/c/analytics/refinery/+/1275815)
The webrequest validation job has evolved and we now need two thresholds, the existing one for data loss with no value change, and a new one for bad-requests as we receive many more (see parent task).
Bug: T422030