fix: Fix LDAP sync when creating new users

[marien-probesys]

Related issue(s)

#763

How to test manually

1. Create a default user role
2. Setup a LDAP server
3. Make sure the LDAP users' emails are not handled by any organization (e.g. no * domain)
4. Synchronize the LDAP users
5. Verify that the synchronization doesn't fail

Checklist

• code is manually tested
• permissions / authorizations are verified
• data can be imported correctly
• interface works on both mobiles and big screens
• interface works in both light and dark modes
• interface works on both Firefox and Chrome
• accessibility has been tested
• tests are up-to-date
• locales are synchronized
• copyright notices are up to date
• documentation is up to date (including migration notes)