Fix flaky test

[jackshirazi]

closes #2458

[trask]

@jackshirazi does the CI failure on this PR look like same or different issue than you were trying to fix here? https://scans.gradle.com/s/gfqf5jlzidn6q

[jackshirazi]

it's related. I left shutdown() instead of shutdownNow() which meant the previous test session can on occasion not finish before the next is started. I've added an interrupt for that too with the latest commit

[trask]

another failure in the latest SamplingProfilerTest: https://scans.gradle.com/s/2dbaqboab5fr6

[jackshirazi]

lol, this is not getting better

[jackshirazi]

@SylvainJuge and/or @JonasKunz I need a careful review, this has turned into significantly more extensive changes than I expected. there's a bunch of different things

• the change to let the test framework to handle the temp dir - that's standard and should be solid
• the changes to better manage interrupts, including a new lock - should be good, there's a chunk of them but I don't think there's anything that can be negative there
• the changes to ensure profiler is stopped - should be fine
• the change to handle empty jfr files - should be fine
• the PostProcessing management changes - this worries me a little, especially the setProfilingSessionOngoing(postProcessingEnabled) to setProfilingSessionOngoing(true) change; it seems to be needed to avoid flaking, and doesn't have any bad effects as far as I can tell by working through code paths, but I need that to be considered carefully
• the ProfilingActivationListener.ensureInitialized() is only in the test framework, so should be fine