Use nuget release of netfx ref package (#10024)

build/dependencies.props

@@ -165,7 +165,7 @@
     <MicrosoftNETCoreApp21PackageVersion>2.1.10</MicrosoftNETCoreApp21PackageVersion>
     <MicrosoftNETCoreDotNetAppHost21PackageVersion>$(MicrosoftNETCoreApp21PackageVersion)</MicrosoftNETCoreDotNetAppHost21PackageVersion>
     <MicrosoftNETCoreWindowsApiSetsPackageVersion>1.0.1</MicrosoftNETCoreWindowsApiSetsPackageVersion>
-    <MicrosoftNETFrameworkReferenceAssembliesPackageVersion>1.0.0-alpha-5</MicrosoftNETFrameworkReferenceAssembliesPackageVersion>
+    <MicrosoftNETFrameworkReferenceAssembliesPackageVersion>1.0.0-preview.1</MicrosoftNETFrameworkReferenceAssembliesPackageVersion>
     <MicrosoftNETTestSdkPackageVersion>15.9.0</MicrosoftNETTestSdkPackageVersion>
     <MicrosoftOwinSecurityCookiesPackageVersion>3.0.1</MicrosoftOwinSecurityCookiesPackageVersion>
     <MicrosoftOwinSecurityPackageVersion>3.0.1</MicrosoftOwinSecurityPackageVersion>

build/sources.props

@@ -20,7 +20,6 @@
       https://dotnet.myget.org/F/aspnetcore-tools/api/v3/index.json;
       https://dotnet.myget.org/F/aspnetcore-master/api/v3/index.json;
       https://dotnet.myget.org/F/roslyn/api/v3/index.json;
-      https://dotnet.myget.org/F/roslyn-tools/api/v3/index.json;
       https://vside.myget.org/F/vssdk/api/v3/index.json;
       https://vside.myget.org/F/vsmac/api/v3/index.json
     </RestoreSources>