RESPONDERS: Enable the local negative timeout by default
    
    Instead of letting admins opt-in to caching the local users negatively
    for a long time, let's enable the negative cache by default.
    
    Resolves:
    https://pagure.io/SSSD/sssd/issue/3619
    
    Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>