Mock api during page on load cause all download resource freeze

[atthaboon]

Describe the bug
run mock api will require page interception in chrome.
await page.setRequestInterception(True)
This will cause all download resource freeze if page still loading the resource

To Reproduce
Steps to reproduce the behavior:

1. Goto https://angular.io/
2. run mock api
3. check network resource found download pending

Expected behavior
mock should not freeze any download

[atthaboon]

Still issue under puppeteer library.
puppeteer/puppeteer#5003

Work around:
Need to mock API before page load