drupal 9: Event registration with drupal user creation crashes if using first+last+email dedupe rule
This is pulled out from #186 (closed) since it's not recent and while touching a similar code area it's not exactly the same.
Part of the problem here is it only sends on the email to createUser, but as in the other ticket it already has the contact id so it shouldn't need to do dedupe rules, it's just how to get that contact id to get passed on to synchronizeUFMatch: https://github.com/civicrm/civicrm-core/blob/c0a3d0e01a7d8df34786a1510d8a4661dffee82b/CRM/Event/Form/Registration.php#L807. Using $_POST is not great, but it needs to be something that gets passed on from the drupal insert hook. And it would be nice to re-use whatever mechanism for the contact user add task too.