v4.3.0: revert change groups many-many to many-1

[Kloppi313]

Hello,
with the release https://github.com/netbox-community/netbox/releases/tag/v4.3.0 there is the breaking change
The group foreign key on the Contact model has been replaced with a many-to-many groups field.
I understand there are usecases for this change. We use it as field for a primary group to unix users.
Unfortunally I am now looking for a way to limit this field back to many-1 relation (one user can be member of one group but one group has several members).
As a beginner I think the solution would be permissions and constraints: https://netboxlabs.com/docs/netbox/administration/permissions/#constraints but I am not able to find a way to limit the count of the memberhips of a user (I dont know django - can only adapt some code).
Am I looking on the right settings (maybe there is a setting to turn the behaviour back)? And could someone please push me a bit further to the solution?