Use PackageLicenseExpression instead of URL (#42277)

Author: ericstj

Directory.Build.props

@@ -197,13 +197,6 @@
 
   <Import Project="Sdk.props" Sdk="Microsoft.DotNet.Arcade.Sdk" />
 
-  <PropertyGroup Condition="'$(CopyrightNetFoundation)' != ''">
-    <Copyright>$(CopyrightNetFoundation)</Copyright>
-    <!-- Temporarily disable PackageLicenseExpression until we can workaround 
-         https://github.com/NuGet/Home/issues/7894 -->
-    <!-- PackageLicenseExpression>MIT</PackageLicenseExpression -->
-  </PropertyGroup>
-
   <!-- Import packaging props -->
   <Import Project="$(RepositoryEngineeringDir)Packaging.props" />
 

eng/Packaging.props

@@ -6,7 +6,8 @@
     <RuntimeIdGraphDefinitionFile>$(RepoRoot)pkg/Microsoft.NETCore.Platforms/runtime.json</RuntimeIdGraphDefinitionFile>
     <ReleaseNotes>https://go.microsoft.com/fwlink/?LinkID=799421</ReleaseNotes>
     <ProjectUrl>https://github.com/dotnet/corefx</ProjectUrl>
-    <LicenseUrl>https://github.com/dotnet/corefx/blob/master/LICENSE.TXT</LicenseUrl>
+    <Copyright>$(CopyrightNetFoundation)</Copyright>
+    <PackageLicenseExpression>MIT</PackageLicenseExpression>
     <!-- defined in buildtools packaging.targets, but we need this before targets are imported -->
     <PackagePlatform Condition="'$(PackagePlatform)' == ''">$(Platform)</PackagePlatform>
     <PackagePlatform Condition="'$(PackagePlatform)' == 'amd64'">x64</PackagePlatform>