core: remove no-mutation-events audit & js callstack method

[patrickhulce]

Summary

• The no-mutation-events audit is the only audit using a large chunk of heavy/slow gatherer code.
• Only 0.8% (3,370/435,697) of sites in HTTPArchive have even a single mutation event listener.
• The gatherer would need fixing to land core: enable async stacks #5504
• All the similar DBW audits were replaced by Chrome violations

If this becomes a priority again after passing our new audit process standards, then we still have this diff to look back on or it can become a Chrome violation to be picked up for free :)

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comment from the future (paul in nov 2021): this PR also removes some captureJSCallUsage() weird stuff . it relied on Error.prepareStackTrace which is a wild lil API. We also found that some websites overwrite window.Error with something and this caused problems: #1194

This PR removes all that so those websites can continue to be a menace but we no longer care.

[paulirish]

sgtm. can you file an issue for adding a violation to Chrome for use of mutation events?

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you have a few more lines to remove in dbw_tester.js

[patrickhulce]

you have a few more lines to remove in dbw_tester.js

done

https://bugs.chromium.org/p/chromium/issues/detail?id=719009

[paulirish]

you have a few more lines to remove in dbw_tester.js

done

pushed?

[patrickhulce]

pushed now

What were your mutation event listener findings? :)

[patrickhulce]

@brendankenny you were 👍 on this, right?

[brendankenny]

it looks like event-helpers might be only used in the audit as well?

Also need to delete the EventListeners artifact in artifacts.d.ts

[brendankenny]

otherwise LGTM!

[patrickhulce]

it looks like event-helpers might be only used in the audit as well?

the things I can still learn exist 😮