Revert rebootstraping to use stage 1 output instead of stage 2

[mthalman]

The changes in https://dev.azure.com/dnceng/internal/_git/dotnet-release/pullrequest/51142 (internal link) should be reverted once the changes in dotnet/roslyn#79119 are in the VMR.

[MichaelSimons]

Fixed with https://dev.azure.com/dnceng/internal/_git/dotnet-release/pullrequest/51411