Revert "[build] Use Xcode toolchain Python executables"
Revert "[build] Use Xcode toolchain Python executables"

xwu/swift,JGiola/swift,tkremenek/swift,hooman/swift,hooman/swift,ahoppen/swift,xwu/swift,rudkx/swift,tkremenek/swift,xwu/swift,roambotics/swift,hooman/swift,atrick/swift,rudkx/swift,xwu/swift,roambotics/swift,roambotics/swift,gregomni/swift,rudkx/swift,tkremenek/swift,parkera/swift,glessard/swift,parkera/swift,JGiola/swift,glessard/swift,tkremenek/swift,hooman/swift,ahoppen/swift,benlangmuir/swift,JGiola/swift,gregomni/swift,roambotics/swift,apple/swift,glessard/swift,benlangmuir/swift,apple/swift,ahoppen/swift,parkera/swift,tkremenek/swift,gregomni/swift,gregomni/swift,glessard/swift,atrick/swift,atrick/swift,parkera/swift,benlangmuir/swift,roambotics/swift,benlangmuir/swift,JGiola/swift,parkera/swift,rudkx/swift,hooman/swift,hooman/swift,JGiola/swift,gregomni/swift,xwu/swift,xwu/swift,roambotics/swift,ahoppen/swift,hooman/swift,rudkx/swift,benlangmuir/swift,benlangmuir/swift,tkremenek/swift,parkera/swift,xwu/swift,apple/swift,ahoppen/swift,apple/swift,rudkx/swift,apple/swift,atrick/swift,atrick/swift,glessard/swift,JGiola/swift,ahoppen/swift,glessard/swift,apple/swift,tkremenek/swift,atrick/swift,gregomni/swift,parkera/swift,parkera/swift