core(trace-processing): add backport for pubads

[adamraine]

Looks like #14693 broke pubads which was causing the errors in our e2e tests. This is a hacky workaround to fix pubads on main.

Our smokes didn't catch this because we don't check any pubads audits that use trace processing.

We could also just revert #14693, doesn't seem super important.

[brendankenny]

Good call on getting it into smoke tests. Can we update pubads? We are still (in theory - #14375) going to get an official release there)

[adamraine]

I guess we could, pubads is already using a dev version of lighthouse:
https://github.com/googleads/publisher-ads-lighthouse-plugin/blob/f05bf852f0e9e772a14ab408d55b0852672daac6/package.json#L25

[adamraine]

So there are a lot of changes we would need to make for pubads to work with the latest dev release of LH (not just this trace processor stuff). I would prefer to keep the backport and do those changes when 10.0 is released officially.

[connorjclark]

Are we to ask them to do an official release where the pinned version for the LH dep is one of our nightlies? And then post-10.0, we can change that to 10.0 proper?

[brendankenny]

I would prefer to keep the backport and do those changes when 10.0 is released officially.

That seems fine, maybe just add a note to #14375 to get rid of the workaround?

This probably warrants a discussion about testing for plugin compatibility when we're explicitly working on a major version release with breaking changes. For 11.0, for instance, should we just disable the pubads tests and reenable when there's a release supporting 11? Downside is we wouldn't catch unexpected regressions, but I'm not sure how likely that is given that we should have pretty good coverage for the artifacts they need, etc.