[12.x] Fix infinite recursion when defining model scope with attribute as private

[noefleury]

The following code was crashing due to an infinite recursion :

class DummyModel extends Model
{

    #[Scope]
    private function myScope(Builder $builder)
    {
        return $builder;
    }

}

DummyModel::query()->myScope();

It was recursively going to resolve the scope through the ___call model method.

As the scope is private it was detected through reflection but each time trying to call it we fallback into __call again.