Remove waitForTimeout usages and implementation

[timvandermeij]

In #17655 we had to implement a waitForTimeout helper function ourselves because Puppeteer 22+ no longer provides it. Waiting for an arbitrary amount of time is discouraged because of what we already found before: it can cause intermittently failing tests if the timeout is too low, and it can add extra runtime to the tests if the timeout is too large. In puppeteer/puppeteer#11780 better alternatives are listed.

Fortunately back when we fixed the intermittent failures in the integration tests we already replaced most occurrences with waitForSelector instead, and we have seen the integration tests being very stable since, but this issue tracks removing the remaining occurrences so we can eventually get rid of the helper function altogether and further reduce any possible flakiness.

[Snuffleupagus]

Would it make sense to add an test/integration/.eslintrc file with a "no-restricted-syntax" rule, see e.g. these ones, that prevents waitForTimeout without a disable-comment?

We'd obviously need to add a bunch of disable-comments all over the tests for now, but it'd be more difficult to accidentally add new waitForTimeout calls.

[timvandermeij]

Would it make sense to add an test/integration/.eslintrc file with a "no-restricted-syntax" rule, see e.g. these ones, that prevents waitForTimeout without a disable-comment?

We'd obviously need to add a bunch of disable-comments all over the tests for now, but it'd be more difficult to accidentally add new waitForTimeout calls.

I think that's a great idea! I have implemented it in the PR above so we indeed make sure that the scope of this issue won't accidentally become bigger.