Set default LDAP password grace period to -1
    
    This will retain existing behavior where LDAP passwords are
    allowed to bind past expiration.
    
    Fixes: https://pagure.io/freeipa/issue/1539
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>