Saving "Bulk-subscribe all unsubscribed users" does the opposite

Same here.
* Doesn't subscribe all users.
* Deselects existing content type settings

Same here:
* Doesn’t subscribe all users
* Removes all items from the notify_subscriptions table

In addition, even when submitting “Submit configurations” on the /admin/config/people/notify/users page without ticking “Bulk-subscribe all unsubscribed users”, all items are still removed from the notify_subscriptions table. I think that the cause is:
- The setUserNotify() method interprets the absence of subscription values as a request to delete all subscriptions
- The UsersForm only passes basic notification settings and does not include subscription information

I’ve created a patch that does the following:
- Adds a check in setUserNotify() to only process subscriptions if subscription values are present
- Prevents unintended deletion of subscriptions while maintaining compatibility with existing functionality

Note: This patch only addresses the removal of items from the notify_subscriptions table when using “Submit configurations” on the /admin/config/people/notify/users page. It does not resolve the issue of users not being subscribed when ticking “Bulk-subscribe all unsubscribed users.”