Remove fake image from converted gsplat camera

[shumash]

This line is unnecessary, remove fake image to avoid memory overhead:
https://github.com/NVIDIAGameWorks/kaolin/blob/master/kaolin/render/camera/gsplats.py#L58

[shumash]

E.g. constructor can work as follows:

    return GSCamera(colmap_id=0,
                    R=R, T=T, FoVx=fovx, FoVy=fovy,
                    image=torch.zeros((3, height, width)) if needs_fake_image else None,  # fake
                    data_device=device,
                    gt_alpha_mask=None, image_name='fake', uid=0,
                    width=width, height=height)