`user_saml` app disabled on upgrade process (27 > 28) caused all users Favorites to be deleted

[solracsf]

Steps to reproduce

1. Upgrade to a major version (27 > 28) from the CLI
2. App is disabled as "not compatible" (but it is) by the upgrade script, and re-enabled after also by the script
3. In the meanwhile, all users Favorites (at least) where lost because deleted by the Cleanup step.

See also #7615 (comment)

[blizzz]

May I assume the app store was not reachable at the time of upgrade, hence user_saml could not be upgraded, ending up in this state.

[blizzz]

I am moving this to the server repository, as the saml backend is an unlucky victim.