Add min/max to reset token script

Allow parallel running of scripts by gu_id offset, to hopefully speed
this up.

Also watch for lag on centralauth db instead of the wiki's db.

Change-Id: I184b811e9e5b9fcbcdb6c06ebcbe002b3606ce75
(cherry picked from commit e25c29926d24ba49f6c8086ae36809f9131fbd65)