Follow up for #35888 to re-enable more test, and re-enable post processors after #36792 has better support for document.gIP with react 18. Apply post-pocessing when the the shell chunk is fully buffered.
re-enabled integration tests for react 18:
- amphtml
- amphtml-custom-optimizer
- app-document
- font-optimization
Fixes#35835
## Bug
- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`
This updates our `yarn next` command to leverage react v18 by default and removes the need for the test require hook/config modifying when testing react 18. There are some fixtures we need to investigate react 18 support in follow-ups:
- `test/integration/client-navigation-a11y`
- `test/integration/critical-css`
- `test/integration/custom-error-page-exception`
- `test/integration/font-optimization`
- AMP specific tests
