[webaudio-testharness] Migrate biquad-basic.html

This CL replaces the use of audit.js with testharness.js in the
basic BiquadFilterNode properties test. The logic and structure of
the original test are preserved, including all assertions and
comments.

Bug: 396477778
Change-Id: I751448ad603f60060cc3b5c903bf1b35c3e010ee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6720942
Reviewed-by: Michael Wilson <mjwilson@chromium.org>
Reviewed-by: Hongchan Choi <hongchan@chromium.org>
Commit-Queue: Punith Nayak <punithbnayak@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1492396}