fix "all configurations" build parameter (#36535)
fix "all configurations" build parameter (#36535)

looks like this changed at some point from "BuildAllConfigurations" to just "allconfigurations"
ericstj/corefx,ViktorHofer/corefx,ViktorHofer/corefx,shimingsg/corefx,wtgodbe/corefx,ericstj/corefx,shimingsg/corefx,ViktorHofer/corefx,BrennanConroy/corefx,ericstj/corefx,wtgodbe/corefx,BrennanConroy/corefx,shimingsg/corefx,ericstj/corefx,ericstj/corefx,ericstj/corefx,ViktorHofer/corefx,BrennanConroy/corefx,ericstj/corefx,wtgodbe/corefx,wtgodbe/corefx,wtgodbe/corefx,shimingsg/corefx,ViktorHofer/corefx,shimingsg/corefx,shimingsg/corefx,ViktorHofer/corefx,ViktorHofer/corefx,shimingsg/corefx,wtgodbe/corefx,wtgodbe/corefx