ChildSafetyHandles grow indefinitely when repeatedly creating and disposing NativeLists with a long‑lived custom allocator

Reproduction steps:
1. Open the attached "IN-129541-REPRO-V3.zip" project
2. Open the “Assets/Scenes/Scene.unity”
3. Open the Task Manager
4. Enter Play mode
5. Observe the result in Task Manager, in the Processes tab

Actual result: Memory allocation constantly increases (about 35 MB/s)
Expected result: Memory allocation remains stable

Reproducible with: 2.4.0 (6000.0.16f1), 2.6.4 (6000.0.67f1, 6000.3.8f1), 6.5.0 (6000.4.0b8, 6000.5.0a6)

Reproduced on: Windows 11
Not reproducible on: No other environments tested