Remove references to SymUploader and the tasks it provided

[hoyosjs]

[hoyosjs]

The other think I can do is leave the targets and make them error out.

[mmitche]

I think making them error out makes more sense. There is one hiccup and I'd like @JoeRobich to chime in.

Roslyn has been using the PublishSymbols tasks in dry run mode in PRs to validate their symbol publishing exclusions: See https://github.com/dotnet/roslyn/pull/75096#discussion_r1757596355 for info.

Is there something else we could add to Publish.proj to keep this kind of validation without keeping the task or references?

[JoeRobich]

We are happy to migrate to something different, as long as we can still validate our publishing config at PR time.

[hoyosjs]

This might take a minute to get to - but there's nothing in the sense that the prior one was not really validating exclusions? It had logging - but there's no error. The tool that v3 uses has a dryrun mode that does some level of validation (it unpacks the nupkg, it checks the files would be fed to symbol.exe, and it can do conversion if you want. However, it does not check files have enough information to be symbol-indexed. That's a concern of symbol.exe now.)