We added nodes.disqualification_reason recently, but we didn't add a
corresponding column in the reputations table (despite having a
corresponding `disqualified` column there).
Without this change, the (very useful and informative) assignments to
updateFields.DisqualificationReason in reputations.go have no effect.
Refs: https://github.com/storj/storj/issues/4601
Change-Id: I77404902ca64b56aed72f1de76b303fe82b76aab
