Re-enable C++/CLI test coverage previously gated on VS 2026 toolset availability

[Copilot]

VS 2026 Helix scout queues were failing C++/CLI coverage because tests were broadly disabled behind a temporary skip tied to missing VC tooling. This change removes those temporary disables so the C++/CLI scenarios execute again now that the image/tooling issue has been addressed.

• Re-enable Build test suite C++/CLI coverage

  • Removed Skip from all FullMSBuildOnlyFact tests in:
    • GivenThatWeWantToBuildACppCliProject
    • GivenThatWeWantToBuildACppCliProjectWithTransitiveDeps
    • SourceLinkTests.Cpp

• Re-enable Pack C++/CLI coverage

  • Removed Skip from GivenThatWeWantToPackACppCliProject.It_cannot_pack_the_cppcliproject.

• Re-enable Publish C++/CLI coverage

  • Removed Skip from GivenThatWeWantToPublishACppCliProject.When_referenced_by_csharp_project_it_publishes_and_runs.

• Change shape

  • No product/runtime behavior changes.
  • Test logic and assertions are unchanged; only test gating metadata was updated.

// Before
[FullMSBuildOnlyFact(Skip = "https://github.com/dotnet/sdk/issues/53789")]

// After
[FullMSBuildOnlyFact]

[marcpopMSFT]

These were disabled in main and servicing, then reenabled in main, then codeflow disabled them again. Let's try reenabling.

[Copilot]

Pull request overview

Re-enables previously skipped C++/CLI test coverage across Build/Pack/Publish test suites by removing temporary Skip metadata that was added due to missing VC toolset availability on VS 2026 Helix scout images.

Changes:

• Removed Skip = "https://github.com/dotnet/sdk/issues/53789" from FullMSBuildOnlyFact-gated C++/CLI Build tests.
• Removed the same Skip from the C++/CLI Pack and Publish coverage tests.
• Re-enabled the C++-related SourceLink test by removing the temporary skip.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/Microsoft.NET.Publish.Tests/GivenThatWeWantToPublishACppCliProject.cs	Removes temporary skip to re-enable the C++/CLI publish scenario test.
test/Microsoft.NET.Pack.Tests/GivenThatWeWantToPackACppCliProject.cs	Removes temporary skip to re-enable the C++/CLI pack scenario test.
test/Microsoft.NET.Build.Tests/SourceLinkTests.cs	Removes temporary skip to re-enable the C++ SourceLink test.
test/Microsoft.NET.Build.Tests/GivenThatWeWantToBuildACppCliProjectWithTransitiveDeps.cs	Removes temporary skips to re-enable transitive-deps C++/CLI build validations.
test/Microsoft.NET.Build.Tests/GivenThatWeWantToBuildACppCliProject.cs	Removes temporary skips to re-enable core C++/CLI build coverage scenarios.

[MichaelSimons]

Looks like several of the enabled tests are failing.

[marcpopMSFT]

Looks like several of the enabled tests are failing.

Yeah, I'm a bit confused by that as I had been able to reenable them in April with #53820. They got disabled in the flow to main for some reason (merge problem) but now they are failing again. Did the VS image regress? I'm having copilot dig into the logs to see what it finds.