Fix missing material override after two glb reimports

[Hilderin]

• Fixes Missing material override after two glb reimports #96443

The problem was because both objects in the scene inherited from the same resource. When the first inherited scene was loaded, the MeshInstance3D connected itself to the mesh's changed signal. Then, when the second inherited scene was loaded, the EditorNode called ResourceLoader::load with ResourceFormatLoader::CACHE_MODE_REPLACE_DEEP, forcing the mesh to reload a second time. However, since the first MeshInstance3D was already connected, when the loader updated the name of the mesh, it emitted the changed signal, triggering MeshInstance3D::_mesh_changed. The issue was that set_name was called before the mesh surfaces were loaded, causing the surface_override_materials to be resized to zero on the first MeshInstance3D.

I replaced ResourceFormatLoader::CACHE_MODE_REPLACE_DEEP with ResourceFormatLoader::CACHE_MODE_REPLACE. This should not cause any problems because EditorNode::reload_instances_with_path_in_edited_scenes already reloads every scene in the inherited chain. In fact, this should improve scene reloading since, with the deep parameter, the mesh was being reloaded for each inherited level!

I also retested this MRP that I used to test scene reimportation:
test-godot-blender-reimport-missing-node-v6.zip

[SaracenOne]

LGTM 👍

[SaracenOne]

Good catch, quite a deeply nested problem, but I think this change should be okay (I am a little nervous about what might happen with references to individual resources contained in the reimported scene though; we might need more test cases).

By the way, since you've discovered quite a few edge cases with the system already, consider taking a look at this PR too (#96144). I tested it with the MRP you submitted and I believe it's somewhat related to the point you made. It also should fix the issue with the instanced scene which gets its editable_child's rotation reset upon reimport.

[aaronfranke]

Didn't test but makes sense to me.

[akien-mga]

Thanks!

[akien-mga]

Cherry-picked for 4.3.1.