RemoveUnreferencedLfsObjectsWorker fails every time with a statement timeout

See https://docs.google.com/spreadsheets/d/10dHoAk23vociZWPpsUPMvTg_8z6XvCsFAwuKn6WcSMg/edit#gid=526760124 and https://sentry.gitlab.net/gitlab/gitlabcom/?query=is%3Aunresolved+transaction%3ASidekiq%2FRemoveUnreferencedLfsObjectsWorker.

If this fails all the time, it suggests we're not actually cleaning up LFS objects correctly?