Preserve libnss_usrfiles2 and pam-config
    
    c93a2983 and 841d4303 explain why libnss_usrfiles2 and pam-config
    are to be preserved on Tumbleweed - e2432fd5 removed the conditional
    to resolve rare issues with idempotency on Leap, but wrongly
    constructed the patch to result in _removal_ instead of _preservation_
    of the packages everywhere - hence repair this by removing the
    respective lines from the removal list.
    
    Signed-off-by: Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>