Two copies of source build artifacts tarball appearing in assets directory

[mthalman]

[mthalman]

The fix from dotnet/dotnet#1827 isn't working in offline legs due to permission issues:

rm: cannot remove '/__w/1/a/artifacts/assets/Release/source-build/dotnet-sdk-10.0.100-rc.1.25427.103-ubuntu.24.04-x64.tar.gz': Permission denied
rm: cannot remove '/__w/1/a/artifacts/assets/Release/source-build/Private.SourceBuilt.Artifacts.10.0.100-rc.1.25427.103.ubuntu.24.04-x64.tar.gz': Permission denied