Merge pull request #29267 from dotnet-maestro-bot/merge/release/3.1-to-master

[automated] Merge branch 'release/3.1' => 'master'

Author: dougbu

NuGet.config

@@ -13,5 +13,4 @@
     <!-- Used for the SiteExtension 3.1 bits that are included in the 5.0 build -->
     <add key="dotnet31-transport" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet3.1-transport/nuget/v3/index.json" />
   </packageSources>
-  <disabledPackageSources />
 </configuration>