test_preload_file_with_manual_data_download_pthreads started failing under firefox

[sbc100]

Seems to be something that changed with firefox nightly over the last 24 hours.

Failing with:

+/report_result?exception:NetworkError: WorkerGlobalScope.importScripts: Failed to load worker script at blob:http://localhost:8888/fc65d367-3917-4d2d-bfe4-a911346944e9 (nsresult = 0x80530013) / undefined

See https://app.circleci.com/pipelines/github/emscripten-core/emscripten/26933/workflows/817768c3-cfb7-4b0f-9da2-a70b142e9998/jobs/620047

[sbc100]

Upstream FF bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1824839

[sbc100]

Fixed in #19088