Consolidate Umami performance tests

Had test failures that only happened on gitlab and not locally, tried various attempts at sleep() to see if it was a race condition all of which failed. What worked was changing a full ::rebuildAll() to just emptying cache bins (i.e. skipping router, twig and container rebuild mostly). Given we have a successful cold cache test where it really does start just after a full rebuilt, it's a pretty minimal change to the test to get the timings down.

This gets the second of two FunctionalJavascript jobs down to ~3m20s from about ~4m10s usually and will allow the special performance test runner job to finish a fair bit quicker too - although won't be able to see by how much until after it's committed.

https://git.drupalcode.org/project/drupal/-/jobs/2210833

Essentially the same tests before/after. #4 makes sense. LGTM.

nod_ → closed merge request !8890

Committed and pushed 27fcad90d9 to 11.x and fd1bcbe5aa to 10.4.x. Thanks!

Due to the way 📌 Use artifacts to share the phpstan result and cspell caches from core to MRs Downport / gitlab artifacts / the performance test job interact, I had to move the main performance jobs to 11.0.x/10.3.x instead of 11.x/10.4.x at least for now. Given that, it'd be useful to backport this to 11.0.x too.

went ahead and backported this to 10.3.x to keep things in sync (and save some CI minutes).

Automatically closed - issue fixed for 2 weeks with no activity.