Summary: Fixes T1768. This is mostly a data cleanliness issue as duplicate rows don't really do anything, but let's clear it up now. Test Plan: made some duplicate rows by adding the same auditor multiple times. ran ./bin/storage upgrade and it worked perfectly! Reviewers: epriestley Reviewed By: epriestley Subscribers: Korvin, epriestley Maniphest Tasks: T1768 Differential Revision: https://secure.phabricator.com/D10849