https://gerrit.wikimedia.org/r/#/c/409710/ broke the updating of ss_total_pages due to a misnamed array parameter key of total vs pages.
- Evaluate whether this could/should be a run-time failure (e.g. unknown parameter being set).
- Add PHPUnit test to verify that this works going forward (e.g. make an edit, trigger updates/jobs, assert)
(Issue was fixed in https://gerrit.wikimedia.org/r/#/c/411400/)