bitECS: drop-in object can be placed at the top

[takahirox]

Description

With the new loader enabled, if I drop-in image_with_controls.zip or
image_without_controls.zip (shared by Imaginer @Exairnous) an object is placed at the top.

This problem was found when investigating #6338, but controls property seems to be unrelated because the problem happens both with and without controls. (image might be related?)

I'm not sure what factor causes it, because I had never seen this problem before.

I tested with this scene https://hubs.mozilla.com/scenes/is67Y4x/conference-room-sb22

To Reproduce
Steps to reproduce the behavior:

1. Enter a room with the new loader enabled
2. Upload the asset file above
3. Confirm that an object is placed at the top

Expected behavior

An object is placed at center as with the old loader

Hardware

• Device: Desktop
• OS: Windows
• Browser: Chrome

Additional context

This issue could be P1 if always happens, but it seems to happen in only a certain case so I didn't add P1 for now.