Revert "Produce 2.1.0-preview3-* packages"
Revert "Produce 2.1.0-preview3-* packages"

This reverts commit 98373de46ff615ea05eed9d1329c9d74426039e3.

We still want to produce preview2 packages in release/2.1 branch
for now.

nguerrera/buildtools,ericstj/buildtools,dotnet/buildtools,stephentoub/buildtools,ericstj/buildtools,nguerrera/buildtools,ericstj/buildtools,ericstj/buildtools,weshaggard/buildtools,dotnet/buildtools,weshaggard/buildtools,crummel/dotnet_buildtools,stephentoub/buildtools,dotnet/buildtools,crummel/dotnet_buildtools,weshaggard/buildtools,crummel/dotnet_buildtools,nguerrera/buildtools,weshaggard/buildtools,dotnet/buildtools,stephentoub/buildtools,stephentoub/buildtools,nguerrera/buildtools,crummel/dotnet_buildtools