Further improvements for automatic repository checks
As discussed with @pcarranza
- RepositoryCheck::BatchWorker should abort its run if more than 10 projects failed their check
- BatchWorker should schedule a single delayed retry for each failed project (safe because we limit the number of failures per batch)
- create RepositoryCheck::ScheduleWorker and put that in sidekiq-cron instead of BatchWorker. To avoid issues where sidekiq-cron restarts / terminates BatchWorker.