EEVEE: Fix pointcloud rendering for Vulkan

When using Vulkan the point clouds were not drawn correctly
in EEVEE. The reason is that only the back faces were drawn.

Pull Request: https://projects.blender.org/blender/blender/pulls/145787

source/blender/draw/engines/eevee/eevee_sync.cc

@@ -279,6 +279,7 @@ void SyncModule::sync_pointcloud(Object *ob, ObjectHandle &ob_handle, const Obje
       object_pass.draw(geometry, res_handle);
     }
     else {
+      object_pass.push_constant("ptcloud_backface", false);
       object_pass.draw(geometry, res_handle);
     }
   };