Flaky: KeyedNotInParallelCrossPhaseTests kills its test process after 30 s on Windows CI (reflection mode) #7166

What happened

In run 39337171332 (PR #7150, modularpipeline (windows-latest)), both tests in tests/TUnit.Engine.Tests/Scheduling/KeyedNotInParallelCrossPhaseTests.cs failed in reflection mode with:

Command execution canceled. Underlying process (TUnit.TestProject.exe#13616) was forcefully terminated.
Command Input: ...TUnit.TestProject.exe --treenode-filter /*/*/Repro5700/* ... --reflection

The tests took 30.3 s, so the 30 s CancellationTokenSource in each test (WithForcefulCancellationToken) killed the child process. No test assertion failed. The same commit passed on ubuntu, and the tests pass locally in both modes in about 3.5 s. The PR does not touch scheduling.

Why

The 30 s budget covers starting a whole TUnit.TestProject process, plus reflection discovery of the full assembly. On a loaded Windows runner, that takes longer than 30 s, even though the filtered class itself runs in milliseconds.

Expected

These regression tests should fail only when the keyed NotInParallel scheduling actually serialises (the #5700 regression), not when process start-up and discovery are slow. Options:

• raise the budget (for example to 2 min). A real deadlock still hangs well past that.
• or measure the overlap inside the test classes (timestamps) instead of using wall-clock process time.

Reproduce

Not reliably reproducible locally. Seen once on Windows CI so far.