repo-updater: Soft-delete repos in fake store
Created by: keegancsmith
This switches the implementation of our fake store to do soft deletion. All our tests continue to work, and this is work towards supporting soft deleting repos in the syncer. When we add soft delete to the DB store, we will add tests that will fail unless soft deletion is working.
Part of https://github.com/sourcegraph/sourcegraph/issues/6859