[vcpkg-tool] x-test-features fails if dependencies are unsupported on current triplet

**Describe the bug**

I noticed that `x-test-features` fails during multiple CI runs if the edited port wasn't marked as unsupported on a given triplet but its dependencies are unsupported on that platform.

For example https://dev.azure.com/vcpkg/public/_build/results?buildId=114840&view=logs&jobId=f3185963-cf64-542d-738a-b43a7110d124&j=f3185963-cf64-542d-738a-b43a7110d124&t=01fe6d08-3359-5d92-0c0d-59657c90ee82

**Expected behavior**

I would expect `x-test-features` to skip triplets on which a given port is unsupported due to its dependencies being unsupported.

Alternatively, if this behavior is expected, all 'unexpectedly cascading' ports should be added to `ci.feature.baseline.txt` to avoid unneccessarry failures during CI runs.