historically, repos were added to the DB without much information and could stay in a broken state until manually removed. If a repo is updating, it should have a cert. So only repos that never did a single index update don't have a cert. Nowadays, this can not happen anymore as we get the repo and its cert before adding it to the DB. So whenever we update a repo, we know its certificate and fingerprint. Thus, this includes a DB migration removing all broken repos and making the certificate for repos in the DB non-null.
and remove sharedTest symlink hack. The shared tests are now a proper gradle module to avoid issues with using the same source files in different modules.