Originally added in 5b9e6497a. We stopped running the integrity check
before userdata upgrades in c4cc44528 because this new behavior was
breaking upgrades, but it could still be run when coming from the DB
Repair Tool, which could cause problems if, say, you recovered a
database from a computer that had an older version of Zotero and ran the
DB Repair Tool on it. Disabling this for now until we have a better
solution.