use later container registry migration cutoff date

Context

We discovered that some container registries that are newer than the cutoff date are still being routed to the old code path on the registry side: Some Container Registry Repositories Created Af... (gitlab-org/container-registry#744 - closed)

We have released a fix on the registry side, but we need to push forward the date that rails considers a repository to be automatically migrated to the new container registry metadata database. Doing this will cause rails to attempt to migrate repositories created before the new date. This MR will adjust the metrics to allow us to monitor this new tranche of repositories which need to be verified by the import process.