Describe the Bug

system.configuration.configurationmanager.7.0.0 in https://github.com/dotnet/source-build-reference-packages is missing some public types available in the nuget package.
One example being ConfigurationPropertyAttribute - this is as a result causing source build build breaks when we attempt to oboard newest SBRP in msbuild: dotnet/msbuild#8893

The missing type is not added even when I try to regenerate package with generate.cmd -p system.configuration.configurationmanager,7.0.0

Steps to Reproduce

1. https://github.com/dotnet/source-build-reference-packages/blob/main/src/referencePackages/src/system.configuration.configurationmanager/7.0.0/lib/net7.0/System.Configuration.ConfigurationManager.cs
2. Search for ConfigurationPropertyAttribute - missing
3. https://www.fuget.org/packages/System.Configuration.ConfigurationManager/7.0.0/lib/net7.0/System.Configuration.ConfigurationManager.dll/System.Configuration/ConfigurationPropertyAttribute - type is available (and public)