API: Add STRAIGHT_JOIN to ApiQueryUserContribs to avoid planner oddness
For some unknown reason, when the actor table has few enough rows (or
few enough compared to revision_actor_temp) MariaDB 10.1.37 decides it
makes more sense to fetch everything from actor + revision_actor_temp
and filesort rather than fetching the limited number of rows from
We can work around it by telling it to not reorder the query, but then
(unlike in I9da981c0) we also have to reorder it ourselves to put
revision_actor_temp first instead of revision.