Mark animation-worklet/idlharness.any.js as timeout=long

On Chromium CI, this occasionally dips above 6s and times out. Looks
like its just a bit slow, not hanging entirely, so giving it more time
to finish seems ok.

Bug: 1062725
Change-Id: I255dc421733cd0938a34ff02b1154d49327a47d8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2110830Reviewed-by: Robert Ma <robertma@chromium.org>
Commit-Queue: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#752019}

third_party/blink/web_tests/external/wpt/animation-worklet/idlharness.any.js

 // META: script=/resources/WebIDLParser.js
 // META: script=/resources/idlharness.js
+// META: timeout=long
 
 'use strict';