[master] Remove Roslyn and vs-editor MyGet feeds (#2715)

* [master] Remove Roslyn and vs-editor MyGet feeds
also
- switch from deprecated dotnet-core feed to dotnet-tools
- remove the down-level dotnet5 feeds

* Bump Microsoft.Extensions.NonCapturingTimer.Sources version to latest

NuGet.config

@@ -2,18 +2,14 @@
 <configuration>
   <packageSources>
     <clear />
-    <add key="dotnet-core" value="https://dotnetfeed.blob.core.windows.net/dotnet-core/index.json" />
     <add key="dotnet-eng" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json" />
-    <add key="dotnet5" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet5/nuget/v3/index.json" />
-    <add key="dotnet5-transport" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet5-transport/nuget/v3/index.json" />
+    <add key="dotnet-tools" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-tools/nuget/v3/index.json" />
     <add key="dotnet6" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet6/nuget/v3/index.json" />
     <add key="dotnet6-transport" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet6-transport/nuget/v3/index.json" />
     <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
-    <add key="myget-roslyn" value="https://dotnet.myget.org/F/roslyn/api/v3/index.json" />
-    <add key="myget-roslyn-tools" value="https://dotnet.myget.org/F/roslyn-tools/api/v3/index.json" />
     <add key="vssdk" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/vssdk/nuget/v3/index.json" />
     <add key="vs-impl" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/vs-impl/nuget/v3/index.json" />
-    <add key="vs-editor-mac" value="https://www.myget.org/F/vs-editor/api/v3/index.json" />
+    <add key="myget-legacy" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/myget-legacy/nuget/v3/index.json" />
     <!-- Used for the Rich Navigation indexing task -->
     <add key="richnav" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/vs-buildservices/nuget/v3/index.json" />
   </packageSources>

eng/Versions.props

@@ -84,7 +84,7 @@
     Versions below this comment are not managed by automation and can be changed as needed.
   -->
   <PropertyGroup Label="Manual">
-    <MicrosoftExtensionsNonCapturingTimerSourcesPackageVersion>5.0.0-preview.2.20121.3</MicrosoftExtensionsNonCapturingTimerSourcesPackageVersion>
+    <MicrosoftExtensionsNonCapturingTimerSourcesPackageVersion>5.0.0-preview.4.20205.1</MicrosoftExtensionsNonCapturingTimerSourcesPackageVersion>
     <BenchmarkDotNetPackageVersion>0.12.1</BenchmarkDotNetPackageVersion>
     <MicrosoftBuildFrameworkPackageVersion>15.8.166</MicrosoftBuildFrameworkPackageVersion>
     <MicrosoftBuildLocatorPackageVersion>1.2.6</MicrosoftBuildLocatorPackageVersion>