(PDB-4505) Log progress during resource-events-pk migration
(PDB-4505) Log progress during resource-events-pk migration

Log "Migrated X of Y events" roughly once per minute during the
migration so that you can fairly quickly estimate about how long it
might take, and can see that it's making progress.

puppetlabs/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb