Use Combinatorial.MSTest for boolean DataRow tests in Microsoft.DotNet.PackageInstall.Tests

[Evangelink]

Summary

In test/Microsoft.DotNet.PackageInstall.Tests, replace full boolean cartesian-product [DataRow] sets with [CombinatorialData] from the Combinatorial.MSTest package.

What changed

• 23 test methods across 3 files (ToolPackageDownloaderTests.cs, ToolPackageInstallerNugetCacheTests.cs, ToolPackageUninstallerTests.cs) had patterns like:

  [DataRow(false)]
  [DataRow(true)]
  public void SomeTest(bool flag) { ... }

  replaced with:

  [CombinatorialData]
  public void SomeTest(bool flag) { ... }

• The .csproj gains an ItemGroup with <PackageReference Include="Combinatorial.MSTest" /> and <Using Include="Combinatorial.MSTest" />.
• Identical executed test cases — no behavioral change; MSTest will still run the method with both false and true.

Why

[CombinatorialData] is cleaner and scales better: adding a second parameter automatically generates all combinations without manually listing every [DataRow]. This is part of a per-project series converting boolean/enum cartesian [DataRow] sets across the SDK test suite.

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com