Add nuget restore feed as well (#23863)

Author: HaoK

eng/helix/content/runtests.cmd

@@ -28,8 +28,8 @@ echo "Invoking InstallDotNet.ps1 %$arch% %$sdkVersion% %$runtimeVersion% %DOTNET
 powershell.exe -NoProfile -ExecutionPolicy unrestricted -file InstallDotNet.ps1 %$arch% %$sdkVersion% %$runtimeVersion% %DOTNET_ROOT%
 
 set exit_code=0
-echo "Restore: dotnet restore RunTests\RunTests.csproj --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet5/nuget/v3/index.json --ignore-failed-sources..."
-dotnet restore RunTests\RunTests.csproj --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet5/nuget/v3/index.json --ignore-failed-sources
+echo "Restore: dotnet restore RunTests\RunTests.csproj --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet5/nuget/v3/index.json --source https://api.nuget.org/v3/index.json --ignore-failed-sources..."
+dotnet restore RunTests\RunTests.csproj --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet5/nuget/v3/index.json --source https://api.nuget.org/v3/index.json --ignore-failed-sources
 
 echo "Running tests: dotnet run --project RunTests\RunTests.csproj -- --target %$target% --sdk %$sdkVersion% --runtime %$runtimeVersion% --queue %$queue% --arch %$arch% --quarantined %$quarantined% --ef %$ef% --aspnetruntime %$aspnetruntime% --aspnetref %$aspnetref% --helixTimeout %$helixTimeout%..."
 dotnet run --project RunTests\RunTests.csproj -- --target %$target% --sdk %$sdkVersion% --runtime %$runtimeVersion% --queue %$queue% --arch %$arch% --quarantined %$quarantined% --ef %$ef% --aspnetruntime %$aspnetruntime% --aspnetref %$aspnetref% --helixTimeout %$helixTimeout%