Conduct performance testing of k6-browser

[yorugac]

Feature Description

Currently, our understanding of computational resources needed for browser tests is limited. More generally, this is also about improving knowledge of how browser (chromium) works underneath.

So it makes sense to conduct specific tests targeting browser and analyze the results. The intro to this problem was best described by @ankur22 over here: https://github.com/grafana/k6/issues/4628#issuecomment-2824841056

Suggested Solution (optional)

In general, it'd be good to understand the following questions better:

• Is there a baseline resource consumption for the browser? If it exists, what are its values, and if it doesn't, what does it depend on?
• How does resource consumption change with website complexity? And what is 'complexity' in that case?
• How is resource consumption "split" between browser and k6 itself? E.g. in which cases browser will be overloaded and in which cases k6 will be overloaded.

To do such testing, one needs not only k6 but also a suitable website that is complex enough to put some load and is also fully observable. So this issue is likely a prerequisite:

• https://github.com/grafana/k6/issues/4828

Already existing or connected issues / PRs (optional)

• https://github.com/grafana/k6/issues/4628
• https://github.com/grafana/k6/issues/4370
• https://github.com/grafana/k6/issues/4395
• https://github.com/grafana/k6/issues/4239