Temporarily disabling CentOS7.1 PR legs
Temporarily disabling CentOS7.1 PR legs

Due to https://github.com/dotnet/corefx/issues/13395, all CentOS legs are failing in PRs.
gkhanna79/corefx,seanshpark/corefx,Petermarcu/corefx,stone-li/corefx,krytarowski/corefx,elijah6/corefx,richlander/corefx,richlander/corefx,MaggieTsang/corefx,alexperovich/corefx,mmitche/corefx,axelheer/corefx,marksmeltzer/corefx,ravimeda/corefx,stephenmichaelf/corefx,cydhaselton/corefx,ericstj/corefx,elijah6/corefx,billwert/corefx,billwert/corefx,yizhang82/corefx,gkhanna79/corefx,cydhaselton/corefx,Petermarcu/corefx,tijoytom/corefx,Ermiar/corefx,stephenmichaelf/corefx,zhenlan/corefx,yizhang82/corefx,MaggieTsang/corefx,the-dwyer/corefx,axelheer/corefx,wtgodbe/corefx,Jiayili1/corefx,parjong/corefx,rubo/corefx,mmitche/corefx,rahku/corefx,parjong/corefx,JosephTremoulet/corefx,tijoytom/corefx,jlin177/corefx,MaggieTsang/corefx,zhenlan/corefx,nbarbettini/corefx,mazong1123/corefx,krytarowski/corefx,ViktorHofer/corefx,DnlHarvey/corefx,elijah6/corefx,ericstj/corefx,seanshpark/corefx,axelheer/corefx,elijah6/corefx,mmitche/corefx,DnlHarvey/corefx,ravimeda/corefx,twsouthwick/corefx,axelheer/corefx,BrennanConroy/corefx,shimingsg/corefx,Ermiar/corefx,lggomez/corefx,dotnet-bot/corefx,rahku/corefx,shimingsg/corefx,weltkante/corefx,YoupHulsebos/corefx,cydhaselton/corefx,jlin177/corefx,fgreinacher/corefx,rahku/corefx,krytarowski/corefx,rjxby/corefx,tijoytom/corefx,gkhanna79/corefx,rubo/corefx,lggomez/corefx,gkhanna79/corefx,tijoytom/corefx,rahku/corefx,cydhaselton/corefx,elijah6/corefx,zhenlan/corefx,seanshpark/corefx,zhenlan/corefx,MaggieTsang/corefx,zhenlan/corefx,DnlHarvey/corefx,stephenmichaelf/corefx,richlander/corefx,ptoonen/corefx,JosephTremoulet/corefx,ericstj/corefx,Jiayili1/corefx,JosephTremoulet/corefx,nchikanov/corefx,krytarowski/corefx,mazong1123/corefx,Ermiar/corefx,stephenmichaelf/corefx,ravimeda/corefx,dotnet-bot/corefx,stone-li/corefx,lggomez/corefx,MaggieTsang/corefx,YoupHulsebos/corefx,shimingsg/corefx,dotnet-bot/corefx,krk/corefx,lggomez/corefx,nchikanov/corefx,parjong/corefx,nbarbettini/corefx,rjxby/corefx,rahku/corefx,gkhanna79/corefx,marksmeltzer/corefx,shimingsg/corefx,BrennanConroy/corefx,nbarbettini/corefx,twsouthwick/corefx,ravimeda/corefx,the-dwyer/corefx,the-dwyer/corefx,DnlHarvey/corefx,krk/corefx,stone-li/corefx,wtgodbe/corefx,fgreinacher/corefx,Petermarcu/corefx,ptoonen/corefx,ptoonen/corefx,gkhanna79/corefx,dhoehna/corefx,marksmeltzer/corefx,Jiayili1/corefx,stone-li/corefx,nchikanov/corefx,stone-li/corefx,elijah6/corefx,stephenmichaelf/corefx,DnlHarvey/corefx,twsouthwick/corefx,lggomez/corefx,ericstj/corefx,ericstj/corefx,twsouthwick/corefx,elijah6/corefx,YoupHulsebos/corefx,Petermarcu/corefx,ptoonen/corefx,nchikanov/corefx,mmitche/corefx,billwert/corefx,stephenmichaelf/corefx,wtgodbe/corefx,krytarowski/corefx,wtgodbe/corefx,yizhang82/corefx,stephenmichaelf/corefx,rubo/corefx,DnlHarvey/corefx,nbarbettini/corefx,Petermarcu/corefx,jlin177/corefx,shimingsg/corefx,ViktorHofer/corefx,seanshpark/corefx,seanshpark/corefx,mazong1123/corefx,alexperovich/corefx,rjxby/corefx,MaggieTsang/corefx,lggomez/corefx,JosephTremoulet/corefx,shimingsg/corefx,dotnet-bot/corefx,DnlHarvey/corefx,the-dwyer/corefx,shimingsg/corefx,nbarbettini/corefx,wtgodbe/corefx,cydhaselton/corefx,stone-li/corefx,dotnet-bot/corefx,nbarbettini/corefx,ViktorHofer/corefx,yizhang82/corefx,Petermarcu/corefx,krytarowski/corefx,ravimeda/corefx,the-dwyer/corefx,mazong1123/corefx,weltkante/corefx,Jiayili1/corefx,weltkante/corefx,marksmeltzer/corefx,BrennanConroy/corefx,alexperovich/corefx,Petermarcu/corefx,mmitche/corefx,billwert/corefx,mazong1123/corefx,weltkante/corefx,jlin177/corefx,mmitche/corefx,krk/corefx,billwert/corefx,zhenlan/corefx,krk/corefx,Ermiar/corefx,jlin177/corefx,ViktorHofer/corefx,rahku/corefx,parjong/corefx,cydhaselton/corefx,richlander/corefx,ptoonen/corefx,marksmeltzer/corefx,axelheer/corefx,ViktorHofer/corefx,billwert/corefx,tijoytom/corefx,rahku/corefx,alexperovich/corefx,MaggieTsang/corefx,dhoehna/corefx,lggomez/corefx,seanshpark/corefx,tijoytom/corefx,rjxby/corefx,JosephTremoulet/corefx,JosephTremoulet/corefx,twsouthwick/corefx,jlin177/corefx,Ermiar/corefx,dotnet-bot/corefx,ptoonen/corefx,ViktorHofer/corefx,parjong/corefx,krk/corefx,dhoehna/corefx,richlander/corefx,wtgodbe/corefx,jlin177/corefx,nchikanov/corefx,rubo/corefx,the-dwyer/corefx,rubo/corefx,rjxby/corefx,parjong/corefx,Jiayili1/corefx,yizhang82/corefx,gkhanna79/corefx,Ermiar/corefx,axelheer/corefx,ptoonen/corefx,ravimeda/corefx,richlander/corefx,YoupHulsebos/corefx,ericstj/corefx,billwert/corefx,yizhang82/corefx,wtgodbe/corefx,alexperovich/corefx,dhoehna/corefx,twsouthwick/corefx,rjxby/corefx,alexperovich/corefx,fgreinacher/corefx,dotnet-bot/corefx,ViktorHofer/corefx,dhoehna/corefx,marksmeltzer/corefx,weltkante/corefx,nbarbettini/corefx,mazong1123/corefx,marksmeltzer/corefx,YoupHulsebos/corefx,yizhang82/corefx,krytarowski/corefx,mmitche/corefx,krk/corefx,dhoehna/corefx,krk/corefx,cydhaselton/corefx,ericstj/corefx,dhoehna/corefx,weltkante/corefx,nchikanov/corefx,alexperovich/corefx,seanshpark/corefx,YoupHulsebos/corefx,tijoytom/corefx,parjong/corefx,JosephTremoulet/corefx,Jiayili1/corefx,mazong1123/corefx,nchikanov/corefx,fgreinacher/corefx,weltkante/corefx,ravimeda/corefx,rjxby/corefx,zhenlan/corefx,Ermiar/corefx,Jiayili1/corefx,YoupHulsebos/corefx,stone-li/corefx,richlander/corefx,twsouthwick/corefx,the-dwyer/corefx