SDK ships stale copies of .NET packages that are still being built

### Describe the bug
The SDK is shipping an old copy of a number of live built packages from runtime. I checked the SDK folder and task folders and found the following to be out of date:

- System.Collections.Immutable
- System.Reflection.Metadata
- System.Reflection.MetadataLoadContext
- System.ComponentModel.Composition

There may be more.

While I understand that the SDK might want to compile against older assemblies to enable sharing with a host like VS or roslyn - that's only the case when it's *not shipping* those. If it ships the assemblies it needs to ship the latest so that future servicing updates are picked up.

### To Reproduce

Examine the file versions of the files redistributed in the SDK. Check for cases that are older than the packages produced in the same .NET release. (I have some tooling I'm working on to help automate this, but wanted to raise this first as it came up in a separate issue).