test/fetch/long-lived-abort-controller.js is very flaky

[KhafraDev]

it has been failing consistently, ie https://github.com/nodejs/undici/actions/runs/11329027907/job/31503604247?pr=3423

[Uzlopak]

two remarks:

• it fails on latest node22, which we use for code coverage (is coveralls again broken?)
• it could be connected with fastTimers.