Backport "Fix Devise configs that depend on Decidim configs" to v0.26

[lahdeero]

🎩 What? Why?

Backport #9014 to 0.26

📌 Related Issues

#9014

Testing

1. Add config.unconfirmed_access_for = 1338.days to development_app/config/initializers/decidim.rb
2. bundle exec rails c
3. In rails console: Devise.allow_unconfirmed_access_for
4. In rails console: Decidim.unconfirmed_access_for

♥️ Thank you!