Copy/Pasting foreign node behaviour is incorrect

[SaracenOne]

Godot version

f8818f8

System information

Windows 11

Issue description

Currently, the behaviour of the node copy-pasting with respect to certain foreign nodes is incorrect. Given certain scene composition, you can copy paste and node and the ownership of that node will be corrupted; top-level nodes should ALWAYS be assigned as owned by the edited scene, but it is currently possible to copy-paste a foreign node and end up with another foreign node.

Steps to reproduce

Open the example project
Copy one of the lowest level nodes called BaseNode
Paste it onto another BaseNode
The new node should appear yellow, which is incorrect.

Minimal reproduction project

scene_composition.zip