use real wpt test runner in CI

[KhafraDev]

Currently, undici implements its own WPT runner. Like Deno, we should try to run the WPT one directly.

https://web-platform-tests.org/running-tests/index.html
https://github.com/denoland/deno/tree/main/tests/wpt

[amyssnippet]

if this is adressed in #4486 then this can be closed i think