dhcp: filter out DHCP failures
dhcp: filter out DHCP failures

If we don't, we start the system before we have an IP address, and when
we actually do get the IP address, we fail an assert on the _config promise,
which was already fulfilled.

rentongzhang/scylla,kangkot/scylla,phonkee/scylla,phonkee/scylla,leejir/seastar,joerg84/seastar,stamhe/scylla,shaunstanislaus/scylla,raphaelsc/seastar,anzihenry/seastar,kangkot/scylla,linearregression/scylla,norcimo5/seastar,aruanruan/scylla,bzero/seastar,raphaelsc/seastar,syuu1228/seastar,acbellini/seastar,printedheart/seastar,dwdm/scylla,koolhazz/seastar,jonathanleang/seastar,kjniemi/seastar,victorbriz/scylla,scylladb/seastar,dreamsxin/seastar,bowlofstew/seastar,xtao/seastar,norcimo5/seastar,sjperkins/seastar,avikivity/scylla,rentongzhang/scylla,respu/scylla,senseb/scylla,wildinto/seastar,dreamsxin/seastar,bowlofstew/seastar,scylladb/scylla,flashbuckets/seastar,kangkot/scylla,stamhe/seastar,rentongzhang/scylla,eklitzke/scylla,avikivity/scylla,hongliangzhao/seastar,acbellini/seastar,shyamalschandra/seastar,duarten/scylla,stamhe/seastar,dwdm/scylla,guiquanz/scylla,avikivity/seastar,avikivity/scylla,rluta/scylla,justintung/scylla,raphaelsc/seastar,tempbottle/scylla,syuu1228/seastar,asias/scylla,tempbottle/seastar,hongliangzhao/seastar,linearregression/seastar,acbellini/scylla,sjperkins/seastar,kjniemi/scylla,glommer/scylla,xtao/seastar,bowlofstew/seastar,mixja/seastar,kjniemi/scylla,flashbuckets/seastar,joerg84/seastar,kjniemi/seastar,senseb/scylla,linearregression/seastar,anzihenry/seastar,justintung/scylla,linearregression/seastar,jonathanleang/seastar,scylladb/scylla-seastar,xtao/seastar,glommer/scylla,asias/scylla,aruanruan/scylla,dwdm/scylla,mixja/seastar,flashbuckets/seastar,dreamsxin/seastar,dwdm/seastar,scylladb/scylla,linearregression/scylla,wildinto/scylla,anzihenry/seastar,aruanruan/scylla,respu/scylla,ducthangho/imdb,avikivity/seastar,bzero/seastar,kjniemi/scylla,cloudius-systems/seastar,eklitzke/scylla,victorbriz/scylla,norcimo5/seastar,eklitzke/scylla,bowlofstew/scylla,syuu1228/seastar,acbellini/scylla,tempbottle/scylla,phonkee/scylla,tempbottle/seastar,glommer/scylla,bzero/seastar,tempbottle/seastar,hongliangzhao/seastar,stamhe/scylla,linearregression/scylla,duarten/scylla,leejir/seastar,scylladb/scylla,victorbriz/scylla,capturePointer/scylla,chunshengster/seastar,koolhazz/seastar,koolhazz/seastar,slivne/seastar,gwicke/scylla,scylladb/seastar,capturePointer/scylla,stamhe/scylla,respu/scylla,bowlofstew/scylla,shaunstanislaus/scylla,printedheart/seastar,cloudius-systems/seastar,justintung/scylla,shyamalschandra/seastar,tempbottle/scylla,rluta/scylla,ducthangho/imdb,guiquanz/scylla,joerg84/seastar,jonathanleang/seastar,gwicke/scylla,mixja/seastar,wildinto/scylla,sjperkins/seastar,scylladb/scylla-seastar,ducthangho/imdb,senseb/scylla,shaunstanislaus/scylla,stamhe/seastar,gwicke/scylla,scylladb/scylla-seastar,cloudius-systems/seastar,dwdm/seastar,guiquanz/scylla,slivne/seastar,chunshengster/seastar,asias/scylla,raphaelsc/scylla,rluta/scylla,raphaelsc/scylla,chunshengster/seastar,acbellini/scylla,acbellini/seastar,duarten/scylla,scylladb/seastar,dwdm/seastar,slivne/seastar,avikivity/seastar,scylladb/scylla,kjniemi/seastar,wildinto/scylla,printedheart/seastar,bowlofstew/scylla,wildinto/seastar,raphaelsc/scylla,wildinto/seastar,capturePointer/scylla,leejir/seastar,shyamalschandra/seastar