Indicate migration path from D7

This depends upon 📌 Port Spoiler to Drupal 9+ Fixed

This will indicate that Spoiler module upgrades correctly. Which it should, though I need to double-check it.

And again it needs the code from #3368775.

I doublechecked the IDs of both the D7 and the port I wrote in the other issue, they're both the same. As a result, the upgrade should be seamless.

Committed.

Automatically closed - issue fixed for 2 weeks with no activity.