Add in browser rendering performance testing pipeline with SiteSpeed
Recently we've had time to explore web endpoint performance testing and bring it up to the same level as we test API endpoints. This covers web endpoint server performance specifically though at load and not browser rendering performance.
Rendering testing was done with SiteSpeed that we spun down last year as other bigger efforts were being done elsewhere in the company.
However upon review we should bring rendering testing back as it's essentially the other half of the performance picture a user sees. Us owning tests here means we can coordinate them with the GPT areas we test and form that full picture.
Task then is to bring back SiteSpeed test pipelines over at the performance-sitespeed
but also make them more informative. Previous testing didn't really report well for us and just reported that the tests had finished, for this to be useful we should explore if it's possible to set test thresholds and have concise but informative reports.