Bug 1839311 [wpt PR 40635] - Prefetch WPT: use assertSpeculationRulesIsSupported...

Bug 1839311 [wpt PR 40635] - Prefetch WPT: use assertSpeculationRulesIsSupported helper, a=testonly

Automatic update from web-platform-tests
Prefetch WPT: use assertSpeculationRulesIsSupported helper

This helper is shared between prerender and prefetch tests, using a new
utils.js file. We move to the style used in the prerendering tests, of
doing the assertion in a setup() block instead of in each test.

Since this involves touching every file anyway to add the new script,
this CL also sorts the script includes vs. the variant metas.

Bug: 1456579
Change-Id: I5059609c1284c25229728b6508aead834cce23da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4623977
Commit-Queue: Domenic Denicola <domenic@chromium.org>
Reviewed-by: Lingqi Chi <lingqi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1160467}

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wpt-commits: e94623a20f4ab27721987741fbd62060466a5919
wpt-pr: 40635