Use Symfony Process to spawn subprocesses in PhpUnitTestRunner

I recall we fixed it in other parts of core to prepare to next SF version

Landing this in 11.x only so we have the old code still running in 10.2.x, just in case we run into issues we can do side-by-side comparisons between branches.

Committed b8a5017 and pushed to 11.x. Thanks!

longwave → closed merge request !6370

We shouldn't be setting a timeout on test arbitrarily. We have no idea how long contrib and custom tests take (on whichever CI run on or a local machine). This change is disruptive. It also makes a long debugging session annoying.

If we want to add a timeout here - it should be configurable by an environmental variable. And the default probably should be no timeout.

Let's just remove the setTimeout() for now then?

@longwave yep - opened 🐛 Remove new test timeout Needs review to address.

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