Fix GeometryInstance3D Custom AABB assignment in the editor not working

This also fixes error spam when changing Custom AABB on a MeshInstance3D
that has no Mesh resource assigned yet (which is allowed in the editor).
This avoids pitfalls when assigning a custom AABB in a script when
loading meshes at runtime.

servers/rendering/renderer_scene_cull.cpp

@@ -1029,7 +1029,6 @@ inline bool is_geometry_instance(RenderingServer::InstanceType p_type) {
 void RendererSceneCull::instance_set_custom_aabb(RID p_instance, AABB p_aabb) {
 	Instance *instance = instance_owner.get_or_null(p_instance);
 	ERR_FAIL_NULL(instance);
-	ERR_FAIL_COND(!is_geometry_instance(instance->base_type));
 
 	if (p_aabb != AABB()) {
 		// Set custom AABB