Issue #3277035 by phenaproxima, tedbow, chrisfromredfin: Create a validator to check for symlinks anywhere in the project
Issue #3276534 by kunal.sachdev, phenaproxima, Theresa.Grannum: CronUpdater::getMode() should always return a value
Issue #3262542 by phenaproxima: Make AutomaticUpdatesKernelTestBase extend PackageManagerKernelTestBase
Issue #3242724 by kunal.sachdev, phenaproxima, tedbow: Ensure cron runs frequently enough to run updates