Remove CommitHash and SourceCommitUrl assembly metadata attributes

ASP.NET's build infrastructure is generating the following AssemblyMetadataAttributes:

https://github.com/dotnet/aspnetcore/blob/340d161093d01e8c7c9ffea4e4dbb50838d893e9/eng/targets/CSharp.Common.targets#L51-L59

These duplicate information already generated by the official .NET SDK (RepositoryUrl and AssemblyInformationalVersion):

https://github.com/dotnet/sdk/blob/446589256a6fc128d1adffe83551a727ebf7f234/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.GenerateAssemblyInfo.targets#L60-L67
https://github.com/dotnet/sdk/blob/446589256a6fc128d1adffe83551a727ebf7f234/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.GenerateAssemblyInfo.targets#L100-L104

We should remove these attributes from the ASP.NET assemblies since they are duplicated. That way the `dotnet/runtime` ILLink configuration doesn't need to list them when trimming assemblies (https://github.com/dotnet/runtime/pull/50903).

See [this conversation](https://github.com/dotnet/runtime/pull/50903/files#r609789719) for more background.

cc @captainsafia @dougbu @pranavkm @marek-safar