camera.sdf: redundancy between //distortion/center and //lens/intrinsics/c* should be fixed

## Desired behavior

The [//camera/distortion/center](https://github.com/gazebosim/sdformat/blob/sdformat12_12.5.0/sdf/1.9/camera.sdf#L133-L135) and [//camera/lens/intrinsics/cx & //camera/lens/intrinsics/cy](https://github.com/gazebosim/sdformat/blob/sdformat12_12.5.0/sdf/1.9/camera.sdf#L183-L188) parameters describe the same information about the optical center of an image. This can lead to confusion for users and requires duplication of parameter values in order to maintain consistency.

We could consider deprecating one of these parameters and exclusively using the other.

## Alternatives considered

## Implementation suggestion

## Additional context