Qt3D Application Crashes when rendering first frame

Customer application is crashing when using Qt3D.

• I tested every Qt3D example and those work fine on the target device
• I enabled Qt3D logging with `export QT_LOGGING_RULES=Qt3D.*.debug=true`.
• This showed that the Scene itself is set up properly but app crashes when trying to render the first frame

• The crash started to occur when customer was switching from 5.12 to 5.15
• Customer is using 5.15.7 on the target hardware. The latest version of Qt3D for 5.15 is 5.15.9. There haven't been many changes since then.
  However, identified a possible patch that might help:
• dbe025fb6 ("CalcBoundingVolumeJob: don't rely on QChangeArbiter for extent changes", 2022-06-13)

• In Qt 5.14, KDAB introduced a new multithreading architecture https://www.kdab.com/qt-3d-one-too-many-threads/
• It is very likely that the bug was introduced here

• The crash also occurs when commenting out and disabling most of the scene. It always occurs when try to render the first frame (compare Qt3D_crash_log vs Qt3D_crash_log_without_sceneroot)

• The bug is most likely a race condition in the new thread architecture coupled with customer's app specific side conditions on Qt3D initialization
• QThreadPool::globalInstance() is used by some modules. I could be that there might occur some interferences, like with the GStreamer pipeline
• When I set the maximum number of threads from 16 to in 1 in VisualReportApplication.cpp (`QThreadPool::globalInstance()->setMaxThreadCount(16);`)
  The application does not crash but is stuck visually, but reacts to touch events
• Backtraces differ a bit each time the app crashes, but QChangeArbiter (from the new 5.14 Multithreading Architecture) is always involved:

Logs files and backtraces are attached.