### Godot version

4.0.2.stable (7a0977c)

### System information

Ubuntu 22.04, x86_64, LLVM

### Issue description

When performing a dedicated server export with:
- a `ShaderMaterial` (a `canvas_item` shader used on a `Panel` in the example below)
- a build with `disable_3d=yes`

the resulting export gives the following error when run:
```
ERROR: Cannot get class 'PlaceholderMaterial'.
   at: instantiate (core/object/class_db.cpp:326)
ERROR: res://main.tscn:Resource of unrecognized type in file: PlaceholderMaterial.
   at: load (core/io/resource_format_binary.cpp:778)
ERROR: Failed loading resource: res://.godot/exported/206107301/export-3070c538c03ee49b7677ff960a3f5195-main.scn. Make sure resources have been imported by opening the project in the editor at least once.
   at: _load (core/io/resource_loader.cpp:223)
ERROR: Failed loading scene: res://main.tscn
   at: start (main/main.cpp:2965)
```

I would expect things to work here without an error - there's no 3D in use here and a normal export with the same build does run as expected.

### Steps to reproduce

1. Build godot with `disable_3d=yes`.
2. Create a new project, and add a `Panel` node.
3. Add a `canvas_item` shader as the material for the `Panel` node.
4. Perform a dedicated server export using the build from step 1.
5. Run the exported binary and observe the error.

### Minimal reproduction project

[DedicatedServer2DTest.zip](https://github.com/godotengine/godot/files/11597444/DedicatedServer2DTest.zip)

ClassDB::add_compatibility_class("OccluderShapeSphere", "Resource");
	
	
	ClassDB::add_compatibility_class("AnimatedSprite", "AnimatedSprite2D");
	ClassDB::add_compatibility_class("Area", "Area3D");
	ClassDB::add_compatibility_class("ARVRCamera", "XRCamera3D");
	ClassDB::add_compatibility_class("ARVRController", "XRController3D");
	ClassDB::add_compatibility_class("ARVRAnchor", "XRAnchor3D");
	ClassDB::add_compatibility_class("ARVRInterface", "XRInterface");
	ClassDB::add_compatibility_class("ARVROrigin", "XROrigin3D");
	ClassDB::add_compatibility_class("ARVRPositionalTracker", "XRPositionalTracker");
	ClassDB::add_compatibility_class("ARVRServer", "XRServer");
	ClassDB::add_compatibility_class("AStar", "AStar3D");
	ClassDB::add_compatibility_class("BoneAttachment", "BoneAttachment3D");
	ClassDB::add_compatibility_class("BoxShape", "BoxShape3D");
	ClassDB::add_compatibility_class("Camera", "Camera3D");
	ClassDB::add_compatibility_class("CapsuleShape", "CapsuleShape3D");
	ClassDB::add_compatibility_class("ClippedCamera", "ClippedCamera3D");
	ClassDB::add_compatibility_class("CollisionObject", "CollisionObject3D");
	ClassDB::add_compatibility_class("CollisionPolygon", "CollisionPolygon3D");
	ClassDB::add_compatibility_class("CollisionShape", "CollisionShape3D");
	ClassDB::add_compatibility_class("ConcavePolygonShape", "ConcavePolygonShape3D");
	ClassDB::add_compatibility_class("ConeTwistJoint", "ConeTwistJoint3D");
	ClassDB::add_compatibility_class("ConvexPolygonShape", "ConvexPolygonShape3D");
	ClassDB::add_compatibility_class("CPUParticles", "CPUParticles3D");
	ClassDB::add_compatibility_class("CSGBox", "CSGBox3D");
	ClassDB::add_compatibility_class("CSGCombiner", "CSGCombiner3D");
	ClassDB::add_compatibility_class("CSGCylinder", "CSGCylinder3D");
	ClassDB::add_compatibility_class("CSGMesh", "CSGMesh3D");