Debugger visualizer test is failing.

[emilio]

https://github.com/servo/rust-smallvec/actions/runs/27339093433/job/80770932750?pr=411

I think we should disable it for now.

[emilio]

This was added in #286, cc @ridwanabdillahi

It fails on trunk and it prevents patches from landing, so disabling for now.