Tree control focus frame is not clipped by parent container
Godot version
4.1.dev (9b9bb418cb1137e69b5131ec9fa7b41c0396db28)
System information
Ubuntu 22.04, Intel Iris Plus Graphics G7, Wayland
Issue description
The focus frame around the Tree control overflows its parent container, even if it should be clipped due to scrolling.

Steps to reproduce
Create a blank project and a new theme resource, to access the theme preview panel.
Focus on the tree control of the previewed widgets and scroll the whole preview to notice the overflowing frame.
Minimal reproduction project
N/A
Can you reproduce this in 3.5.2?
No, it does not happens in 3.5.2, seems related with the new default theme
https://github.com/godotengine/godot/blob/bc88dca176cef6b8943ded58c68a60f7c127baea/scene/gui/tree.cpp#L4309-L4313
Same happens with RichTextLabel and ItemList. This is related to calling RenderingServer::canvas_item_add_clip_ignore(). Parent controls with clip_contents enabled cannot clip these borders.