Refactor tests

[malcolm-kee]

Bug report

This is to track the bad tests so I will remember to pick this up later.

Right now some tests will hangs when error, because the puppeteer does not cleanup correctly, such as tests in this file: https://github.com/webpack/webpack-dev-server/blob/master/test/e2e/overlay.test.js

We should include some cleanup if the puppeteer is not cleanup due to error.

Actual Behavior

Expected Behavior

How Do We Reproduce?

Please paste the results of npx webpack-cli info here, and mention other relevant information

[alexander-akait]

Yeah, maybe we can merge it with #2843

[malcolm-kee]

I think #2843 would probably need more time, I remembered I was blocked by something related to websocket few weeks back.

Besides, this refactoring itself is already very big 😅

[alexander-akait]

Let's close in favor #2843