Bug New prefab workflow makes PlayableGraph leak in the Editor

When you launch a scene while editing a prefab, Unity does call OnDisable/OnEnable on the opened prefab components, but when you then stop the scene, Unity calls nothing, but invalidates PlayableGraphs, that were created in the prefab's components. Thus making them leak and spamming "PlayableGraph was not destroyed" messages.

But Unity doesn't give any means to actually destroy the graph as no OnDisable gets called. It seems like due to Unity's broken life cycle, the graph is created in "runtime" memory space instead of "editor" and thus leaks when leaving play mode.

Bug report: 1314439