Remove WebTransport tests that return PRECONDITION_FAILED

[jgraham]

Test List

https://wpt.fyi/results/webtransport?label=master&label=experimental&aligned&view=interop&q=label%3Ainterop-2026-webtransport

Rationale

Tests that don't return PASS or FAIL don't work with the scoring system we have. We either need to have these tests return a consistent result or remove them from Interop.

[gsnedders]

Did you mean to link to https://wpt.fyi/results/webtransport?label=master&label=experimental&aligned&view=interop&q=label%3Ainterop-2026-webtransport%20status%3APRECONDITION_FAILED?

[jgraham]

Yes, that seems like the right set of tests :)

[gsnedders]

https://wpt.fyi/results/webtransport/back-forward-cache-with-open-webtransport-connection.https.window.html?run_id=5201252190519296&run_id=6231331980967936&run_id=5147584158236672&run_id=5078112995115008 also just seems kinda broken, given three browsers get:

FAIL message: promise_test: Unhandled rejection with value: object "Error: assert_false is not defined"