Fix a FS3548 'Pattern discard is not allowed for union case that takes no data.' compiler warning

[Numpsy]

Description

ToolType.FullFramework has no payload, so it shouldn't need the discard

[Numpsy]

refs

[Thorium]

Mac build is still unstable. The message which Mac build fails make no sense to this PR.
It's even hard to reason about what it fails to,
no dependencies hello world and casing #2314 failed so it should do "dotnet fake" for very simple file. Seems to work in my MacBook (old Intel).

[Numpsy]

I put some observations about the macOS CI failures in #2814, but I don't know if it's just a timing issue or something else (it doesn't seem to happen on the Windows or Linux riuns though)