WFE2: Restore HeadNonceStatusOK feat. in conf-next (#4011)
WFE2: Restore HeadNonceStatusOK feat. in conf-next (#4011)

This was accidentally removed in 842739bc but hasn't been deployed to
staging/prod yet.
jcjones/boulder,jsha/boulder,bmw/boulder,jsha/boulder,jcjones/boulder,jfrazelle/boulder,jfrazelle/boulder,letsencrypt/boulder,letsencrypt/boulder,letsencrypt/boulder,jfrazelle/boulder,jfrazelle/boulder,jsha/boulder,jcjones/boulder,bmw/boulder,bmw/boulder,jcjones/boulder