dillon1000/react

[mcp] Add proper web-vitals metric collection (#33109)

Multiple things here:
- Improve the mean calculation for metrics so we don't report 0 when
web-vitals fail to be retrieved
- improve ui chaos monkey to use puppeteer APIs since only those trigger
INP/CLS metrics since we need emulated mouse clicks
- Add logic to navigate to a temp page after render since some
web-vitals metrics are only calculated when the page is backgrounded
- Some readability improvements