Clean up sources.props (#1169)

Author: JamesNK

build/sources.props

@@ -3,12 +3,9 @@
     <RestoreSources>
       $(RestoreSources);
       https://api.nuget.org/v3/index.json;
-      https://dotnetfeed.blob.core.windows.net/aspnet-aspnetcore/index.json;
-      https://dotnetfeed.blob.core.windows.net/aspnet-extensions/index.json;
       https://dotnetfeed.blob.core.windows.net/dotnet-core/index.json;
       https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet5/nuget/v3/index.json;
       https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet6/nuget/v3/index.json;
-      https://dotnet.myget.org/F/roslyn/api/v3/index.json;
     </RestoreSources>
     <RestoreSources Condition="Exists('$(MSBuildThisFileDirectory)feed')">
       $(RestoreSources);
@@ -19,12 +16,5 @@
       $(RestoreSources);
       https://grpc.jfrog.io/grpc/api/nuget/v3/grpc-nuget-dev;
     </RestoreSources>
-    <!-- The following is a temporary change so 5.0 build works during transition from rc to rtm -->
-    <RestoreSources>
-      $(RestoreSources);
-      https://pkgs.dev.azure.com/dnceng/public/_packaging/darc-pub-dotnet-runtime-b928f03f/nuget/v3/index.json;
-      https://pkgs.dev.azure.com/dnceng/public/_packaging/darc-pub-dotnet-efcore-ab94ac91/nuget/v3/index.json;
-    </RestoreSources>
   </PropertyGroup>
 </Project>
-