Notification timeouts cannot be changed due to issues with scopes.

Steps:

1. Try to change the default values for notifications timeouts as described in doc. E.g. change success timeout from default 5000 to 0.
2. Reload cache.
3. Try different scopes (default, admin_group, admin).
4. Check success notification after publishing an item.

Actual result: Default timeout of 5000 is still applied.
Expected result: New timeout value is used.

Remarks: It works when timeout is changed directly in vendor/ibexa/admin-ui/src/bundle/Resources/config/ezplatform_default_settings.yaml.