[Release pipeline] Exclude wiki link to smoke test prereqs tarball for .NET 9

[mthalman]

For a .NET 9 release, the wiki page that gets generated for partners includes a link to the feed to download the smoke test prereqs tarball. But we don't publish this tarball for .NET 9. It's only for .NET 8 and earlier. A link to the feed location should be excluded from the generated wiki page.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.