These variables track whether a database migration necessitates a service
restart. The new name avoids confusion with the conditional restart
feature introduced in af193043/9accc848/4a8df138, where
devture_systemd_service_manager handles restarting services whose
configuration or image changed. The old _requires_restart name was
ambiguous — it could be mistaken for the systemd_service_manager
mechanism — so _migration_requires_restart makes the purpose explicit.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>