Auto registration is not working anymore

[jacobo221]

Description: Auto registration is broken

Steps to reproduce:

1. Enable auto registration in the active contest
2. Visit the contest page as a new user and try to register

Expected: The new use should have a new account created

Actual: Creation of the new account fails, seems to be that the SQL query is missing a default group (new feature post-1.5.1)

System Information

CMS version: main
How was CMS installed: docker
Postgres version: 15
Distribution and version: Ubuntu in docker, using official Dockerfile

[prandla]

and i thought i already fixed all the bugs from the groups feature (#1672).... evidently not.

i guess i'll need to finish writing the browser test suite before we can make the next release, this is a bit embarrassing currently 😅