Remove the vs-sdk feed as it's not required and is risky (#51745)

Author: marcpopMSFT

NuGet.config

@@ -57,8 +57,6 @@
     <add key="dotnet-tools-transport" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-tools-transport/nuget/v3/index.json" />
     <add key="dotnet-libraries" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-libraries/nuget/v3/index.json" />
     <add key="dotnet-libraries-transport" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-libraries-transport/nuget/v3/index.json" />
-    <add key="vssdk" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/vssdk/nuget/v3/index.json" />
-    <add key="vssdk-archived" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/vssdk-archived/nuget/v3/index.json" />
     <add key="vs-impl" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/vs-impl/nuget/v3/index.json" />
     <!-- Used for Rich Navigation indexing task -->
     <add key="richnav" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/vs-buildservices/nuget/v3/index.json" />

test/TestAssets/Directory.Build.props

@@ -5,6 +5,7 @@
     <ManagePackageVersionsCentrally>false</ManagePackageVersionsCentrally>
     <CheckEolTargetFramework>false</CheckEolTargetFramework>
     <DefaultItemExcludes>$(DefaultItemExcludes);**/*.tmp</DefaultItemExcludes>
+    <NuGetAudit>false</NuGetAudit> 
   </PropertyGroup>
 
 </Project>