chore: Remove NuGet.Frameworks dependency from test projects (#9276)

* chore: fix NuGet.Frameworks package version

* chore: remove NuGet.Frameworks dependency from test projects

* chore: update test sdk version

* chore: remove NuGet.config file that is used for NuGet.Frameworks

---------

Co-authored-by: Yufei Huang <yufeih@live.com>

Author: filzrev

Directory.Packages.props

@@ -39,9 +39,7 @@
     <PackageVersion Include="coverlet.collector" Version="6.0.0" />
     <PackageVersion Include="FluentAssertions" Version="6.12.0" />
     <PackageVersion Include="Magick.NET-Q16-AnyCPU" Version="13.4.0" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
-    <PackageVersion Include="NuGet.Frameworks" Version="6.8.0-rc.122" Condition="'$(TargetFramework)' != 'net8.0'" />
-    <PackageVersion Include="NuGet.Frameworks" Version="6.8.0-rc.122" Condition="'$(TargetFramework)' == 'net8.0'" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.9.0-preview-23531-01" />
     <PackageVersion Include="Verify.DiffPlex" Version="2.3.0" />
     <PackageVersion Include="Verify.Xunit" Version="22.4.1" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.5.3" />

NuGet.config

@@ -17,16 +17,6 @@
     </PackageReference>
     <PackageReference Include="FluentAssertions" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" />
-    <!--
-      The NuGet.Frameworks package is required to run csproj based tests targeting .NET 7.0.200.
-
-      Microsoft.NET.Test.Sdk bundles an old NuGet.Frameworks package to the output folder,
-      which takes predence over the one shipped with .NET SDK.
-      .NET 7.0.200 SDK depends on a newer NuGet.Frameworks package this is not availble on NuGet.org yet.
-
-      This only impact test since MSBuildLocator will resolve NuGet.Frameworks package from the appropreciate .NET SDK location.
-    -->
-    <PackageReference Include="NuGet.Frameworks" />
     <PackageReference Include="xunit.runner.visualstudio" />
     <PackageReference Include="xunit" />
   </ItemGroup>