Avoid attrs test flakines, stop using info_nss
    
    authtest already sets the fullname attribute,
    just use that one instead of relying on nss which, on test systems
    may have a completely empty gecos field, which makes the test fail.
    
    Signed-off-by: Simo Sorce <simo@redhat.com>
    Reviewed-by: Patrick Uiterwijk <puiterwijk@redhat.com>