Enable dotnet-sos nupkg on community platform

https://github.com/dotnet/diagnostics/blob/8bbc63df036b0c31c865fc1ee0060564caf40f85/src/sos-packaging.props packs all Microsoft supported platforms binaries into a single package, and leaves no room for community supported platforms while doing a local dotnet-sos build by running `./build.sh -pack`. Ideally, it should not "require" all binaries at least during the source-build which only care for a _single_ target platform native lib in the nupkg.

Blocking https://github.com/dotnet/sdk/issues/48986, https://github.com/dotnet/runtime/issues/116293