Puppeteer E2E test: Multi-page in-browser parallelism

[LeviPesin]

Related issue: #24109

Description

Add multi-page parallelism to Puppeteer and also decrease CI parallelism to 4 threads.

[LeviPesin]

Strange that tests fail... Seems like a page is used simultaneously in two attempts (but that should be impossible because of the lock)?..

 file:///home/runner/work/three.js/three.js/node_modules/puppeteer-core/lib/esm/puppeteer/common/ExecutionContext.js:298
        throw new Error('Execution context was destroyed, most likely because of a navigation.');
              ^

Error: Execution context was destroyed, most likely because of a navigation.
    at rewriteError (file:///home/runner/work/three.js/three.js/node_modules/puppeteer-core/lib/esm/puppeteer/common/ExecutionContext.js:298:15)
    at runMicrotasks (<anonymous>)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async ExecutionContext._ExecutionContext_evaluate (file:///home/runner/work/three.js/three.js/node_modules/puppeteer-core/lib/esm/puppeteer/common/ExecutionContext.js:241:56)
    at async ExecutionContext.evaluate (file:///home/runner/work/three.js/three.js/node_modules/puppeteer-core/lib/esm/puppeteer/common/ExecutionContext.js:122:16)
    at async Promise.all (index 0)
    at async file:///home/runner/work/three.js/three.js/test/e2e/puppeteer.js:272:16
Error: Process completed with exit code 1.

[LeviPesin]

Especially strange that I don't see that problem when running locally...
UPD: Seeing it now...

[LeviPesin]

Seems like the Mac problems are related to puppeteer/puppeteer#8693... I will investigate more.

[LeviPesin]

Headful:
First run - 0 has not failed, 1 failed on webgl_materials_video, 2 failed on webgl_multiple_elements_text and webxr_vr_video.
Second run - 0 has not failed, 1 has not failed, 2 failed on webgl_multiple_elements_text and webxr_vr_video.
Third run - 0 failed on webgl2_multisampled_renderbuffers and webgl_buffergeometry_lines, 1 has not failed, 2 failed on webgl_multiple_elements_text, webgpu_nodes_playground, webxr_ar_dragging, and webxr_vr_video.
I think these about-the-same results (and also that fails were NOT due to TimeoutError) mean that the main problem disappears when usnig headful (same as described in puppeteer/puppeteer#8693).
But it also could be that just parallelism somehow stops working in headful...

[LeviPesin]

Hm... Even with multiple browsers instead of multiple pages TimeoutError happens. So maybe it is not puppeteer/puppeteer#8693...

[LeviPesin]

It could be fixed just by increasing networkTimeout 🤦‍♂️ I think it works now. (I will re-run the tests a few times more just to check)

[LeviPesin]

Seems that it works!

[LeviPesin]

Seems like sometimes Mac fails even with a large timeout...

[LeviPesin]

@mrdoob I think we can merge this PR and possibly tweak the number of CI threads, browser pages, and network timeout later. (It should work currently)

[LeviPesin]

Will run tests a few times to see if some examples don't work under new threshold...

[LeviPesin]

@mrdoob Seems to work!