fix(models): don't call clean from another model

since the calling model won't have fields from the called model
any validation errors that bubble will cause additional errors
in the Django Admin

benefits/core/models.py

@@ -625,8 +625,6 @@ def clean(self):
                 field_errors.update(reenrollment_error_template=ValidationError("Required when supports expiration is True."))
 
         if self.transit_agency and self.transit_agency.active:
-            self.transit_agency.clean()
-
             if self.claims_provider:
                 message = "Required for claims verification."
                 needed = dict(