TestAsTools job fails with latest SDK

[sbomer]

See the failures in #3133:

F:\workspace\_work\1\s\src\Tests\Directory.Build.targets(56,5): error MSB3073: The command "dotnet tool install --local testSdkRestore --version 3.0.100-ci --add-source F:\workspace\_work\1\s\artifacts\packages\Debug\NonShipping\" exited with code 1. [F:\workspace\_work\1\s\src\Tests\Microsoft.NET.Restore.Tests\Microsoft.NET.Restore.Tests.csproj]

[wli3]

This is resolved by updating stage 0. #3153