### 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("CSGPolygon", "CSGPolygon3D");
	ClassDB::add_compatibility_class("CSGPrimitive", "CSGPrimitive3D");
	ClassDB::add_compatibility_class("CSGShape", "CSGShape3D");
	ClassDB::add_compatibility_class("CSGSphere", "CSGSphere3D");
	ClassDB::add_compatibility_class("CSGTorus", "CSGTorus3D");
	ClassDB::add_compatibility_class("CubeMesh", "BoxMesh");
	ClassDB::add_compatibility_class("CylinderShape", "CylinderShape3D");
	ClassDB::add_compatibility_class("DirectionalLight", "DirectionalLight3D");
	ClassDB::add_compatibility_class("EditorSpatialGizmo", "EditorNode3DGizmo");
	ClassDB::add_compatibility_class("EditorSpatialGizmoPlugin", "EditorNode3DGizmoPlugin");
	ClassDB::add_compatibility_class("Generic6DOFJoint", "Generic6DOFJoint3D");
	ClassDB::add_compatibility_class("GIProbe", "VoxelGI");
	ClassDB::add_compatibility_class("GIProbeData", "VoxelGIData");
	ClassDB::add_compatibility_class("GradientTexture", "GradientTexture1D");
	ClassDB::add_compatibility_class("HeightMapShape", "HeightMapShape3D");
	ClassDB::add_compatibility_class("HingeJoint", "HingeJoint3D");
	ClassDB::add_compatibility_class("Joint", "Joint3D");
	ClassDB::add_compatibility_class("KinematicBody", "CharacterBody3D");
	ClassDB::add_compatibility_class("KinematicBody2D", "CharacterBody2D");
	ClassDB::add_compatibility_class("KinematicCollision", "KinematicCollision3D");
	ClassDB::add_compatibility_class("Light", "Light3D");
	ClassDB::add_compatibility_class("Light2D", "PointLight2D");
	ClassDB::add_compatibility_class("LineShape2D", "WorldBoundaryShape2D");
	ClassDB::add_compatibility_class("Listener", "AudioListener3D");
	ClassDB::add_compatibility_class("MeshInstance", "MeshInstance3D");
	ClassDB::add_compatibility_class("MultiMeshInstance", "MultiMeshInstance3D");
	ClassDB::add_compatibility_class("NavigationAgent", "NavigationAgent3D");
	ClassDB::add_compatibility_class("NavigationMeshInstance", "NavigationRegion3D");
	ClassDB::add_compatibility_class("NavigationObstacle", "NavigationObstacle3D");
	ClassDB::add_compatibility_class("NavigationPolygonInstance", "NavigationRegion2D");