Puppeteer E2E test: Multi-page in-browser parallelism (#25386)

* Puppeteer: Multi-page parallelism

* Remove CI parallelism

* Some fixes

* Fix the 'Execution context was destroyed' error

* Update logging

* Restore CI parallelism in 2 threads

* More exceptions

* Oops

* Add Mac's own exception list

* Update exceptions

* Update exceptions

* Test headful on Mac

* Test mutiple browsers instead of multiple pages on Mac

* Fix

* Fix

* Fix

* Fix

* Revert

* Try to increase networkTimeout

* Increase CI threads to 4

* Should be fixed now

* Further increase networkTimeout

* Further increase networkTimeout

* TEST: numPages: 8, networkTimeout: 1.5

* TEST: numPages: 8, networkTimeout: 5

* TEST: numPages: 4, networkTimeout: 1.5

* Return to 8-5

* Accidentally removed one exception

* New exception