parallel restore on mac/linux (#49523)
parallel restore on mac/linux (#49523)

Revert of #33109
KirillOsenkov/roslyn,mgoertz-msft/roslyn,wvdd007/roslyn,weltkante/roslyn,weltkante/roslyn,KirillOsenkov/roslyn,KevinRansom/roslyn,mavasani/roslyn,dotnet/roslyn,AlekseyTs/roslyn,mgoertz-msft/roslyn,CyrusNajmabadi/roslyn,mavasani/roslyn,AmadeusW/roslyn,tannergooding/roslyn,shyamnamboodiripad/roslyn,mgoertz-msft/roslyn,sharwell/roslyn,heejaechang/roslyn,KevinRansom/roslyn,panopticoncentral/roslyn,diryboy/roslyn,shyamnamboodiripad/roslyn,dotnet/roslyn,AmadeusW/roslyn,AlekseyTs/roslyn,KirillOsenkov/roslyn,eriawan/roslyn,tannergooding/roslyn,KevinRansom/roslyn,tannergooding/roslyn,jasonmalinowski/roslyn,physhi/roslyn,sharwell/roslyn,sharwell/roslyn,dotnet/roslyn,heejaechang/roslyn,heejaechang/roslyn,shyamnamboodiripad/roslyn,tmat/roslyn,tmat/roslyn,CyrusNajmabadi/roslyn,bartdesmet/roslyn,diryboy/roslyn,ErikSchierboom/roslyn,panopticoncentral/roslyn,CyrusNajmabadi/roslyn,bartdesmet/roslyn,physhi/roslyn,panopticoncentral/roslyn,jasonmalinowski/roslyn,wvdd007/roslyn,wvdd007/roslyn,ErikSchierboom/roslyn,diryboy/roslyn,mavasani/roslyn,eriawan/roslyn,AlekseyTs/roslyn,eriawan/roslyn,ErikSchierboom/roslyn,physhi/roslyn,weltkante/roslyn,AmadeusW/roslyn,tmat/roslyn,bartdesmet/roslyn,jasonmalinowski/roslyn