The field `auth_signup_uninvited` is defined in the 3 aforementioned
modules, yet they are independant modules in respects to one another.
This means that whichever module is installed first will create an XMLID
for the field, if this module is uninstalled before the other two: boom!
crash when changing general settings because the res.config.settings
field set by the other two modules no longer exists.
To solve this, we simply ignore the field during ir_model_field.unlink()
Fixes#23171
