Fix an exploit that let you determine the flagger of a post using
`flagger:<username>` saved searches. Saved searches were performed as
DanbooruBot, but since DanbooruBot is a moderator, it let unprivileged
users do `flagger:<username>` searches. Saved searches were done as a
moderator to avoid tag limits, but this is no longer necessary since the
last PostQueryBuilder refactor.
fred get out