Merge in 'release/3.1' changes

Author: dotnet-bot

NuGet.config

@@ -4,18 +4,10 @@
     <clear />
     <!--Begin: Package sources managed by Dependency Flow automation. Do not edit the sources below.-->
     <!--  Begin: Package sources from dotnet-razor-tooling -->
-    <add key="darc-int-dotnet-razor-tooling-f7f8678" value="https://pkgs.dev.azure.com/dnceng/_packaging/darc-int-dotnet-razor-tooling-f7f86786/nuget/v3/index.json" />
     <!--  End: Package sources from dotnet-razor-tooling -->
     <!--  Begin: Package sources from dotnet-corefx -->
     <!--  End: Package sources from dotnet-corefx -->
     <!--  Begin: Package sources from dotnet-core-setup -->
-    <add key="darc-int-dotnet-core-setup-9165b88" value="https://pkgs.dev.azure.com/dnceng/_packaging/darc-int-dotnet-core-setup-9165b88e/nuget/v3/index.json" />
-    <!--  End: Package sources from dotnet-core-setup -->
-    <!--  Begin: Package sources from dotnet-efcore -->
-    <add key="darc-int-dotnet-efcore-d3511a1" value="https://pkgs.dev.azure.com/dnceng/_packaging/darc-int-dotnet-efcore-d3511a1a/nuget/v3/index.json" />
-    <!--  End: Package sources from dotnet-efcore -->
-    <!--  Begin: Package sources from dotnet-extensions -->
-    <add key="darc-int-dotnet-extensions-fc49d8e" value="https://pkgs.dev.azure.com/dnceng/_packaging/darc-int-dotnet-extensions-fc49d8e2/nuget/v3/index.json" />
     <!--  End: Package sources from dotnet-extensions -->
     <!--End: Package sources managed by Dependency Flow automation. Do not edit the sources above.-->
     <add key="dotnet-eng" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json" />
@@ -27,16 +19,6 @@
     <clear />
     <!--Begin: Package sources managed by Dependency Flow automation. Do not edit the sources below.-->
     <!--  Begin: Package sources from dotnet-razor-tooling -->
-    <add key="darc-int-dotnet-razor-tooling-f7f8678" value="true" />
-    <!--  End: Package sources from dotnet-razor-tooling -->
-    <!--  Begin: Package sources from dotnet-extensions -->
-    <add key="darc-int-dotnet-extensions-fc49d8e" value="true" />
-    <!--  End: Package sources from dotnet-extensions -->
-    <!--  Begin: Package sources from dotnet-efcore -->
-    <add key="darc-int-dotnet-efcore-d3511a1" value="true" />
-    <!--  End: Package sources from dotnet-efcore -->
-    <!--  Begin: Package sources from dotnet-core-setup -->
-    <add key="darc-int-dotnet-core-setup-9165b88" value="true" />
     <!--  End: Package sources from dotnet-core-setup -->
     <!--  Begin: Package sources from dotnet-corefx -->
     <!--  End: Package sources from dotnet-corefx -->