use the shipping urls (#1675)

Author: mattleibow

NuGet.config

@@ -5,7 +5,7 @@
     <!-- <add key="local" value="artifacts" /> -->
     <add key="dotnet-eng" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json" protocolVersion="3" />
     <add key="dotnet-public" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-public/nuget/v3/index.json" protocolVersion="3" />
-    <add key="dotnet6" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet6/nuget/v3/index.json" />
+    <add key="dotnet6" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/6.0.100-preview.6.21355.2-shipping/nuget/v3/index.json" />
     <add key="xamarin" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/xamarin-impl/nuget/v3/index.json" />
     <!-- <add key="reunion-internal" value="https://pkgs.dev.azure.com/microsoft/ProjectReunion/_packaging/Project.Reunion.nuget.internal/nuget/v3/index.json" /> -->
   </packageSources>

src/DotNet/DotNet.csproj

@@ -75,7 +75,7 @@
   <packageSources>
     <clear />
     <add key="local"   value="$(PackageOutputPath)" />
-    <add key="dotnet6" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet6/nuget/v3/index.json" />
+    <add key="dotnet6" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/6.0.100-preview.6.21355.2-shipping/nuget/v3/index.json" />
     <add key="xamarin" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/xamarin-impl/nuget/v3/index.json" />
   </packageSources>
 </configuration>