Thanks. You have meant:
# foreman-maintain content remove-pulp2
That cleared out the migration tables from the database. Too bad, that this isn’t run automatically during upgrades after you have already made the pulp3 migration. The removal of the migration tables must have been added later because I ran remove-pulp2 originally before upgrading to 4.0…
Of course, now I have the orphaned remotes for the two foreman client repos in the database which I have deleted in Katello…