Camera projection shader does not work

**Describe the bug**
In the Solaris viewport, the camera projection shader always uses the render camera. An exported USD file has the wrong camera name for the projection shader ("/stage/projection_camera" instead of "/cameras/projection_camera"). An HDARNOLD_DEBUG_SCENE ass file has no an empty camera_projection.camera parameter.

**To Reproduce**
Steps to reproduce the behavior:
1. You can load the attached Houdini scene. Or kick the attached usd file.

[camera_projection_test.zip](https://github.com/user-attachments/files/15788720/camera_projection_test.zip)

**Used Software Versions**
- Houdini 20.0.688 with latest HtoA

Start by loading the attached Houdini scene or kicking the attached USD file to reproduce the Solaris viewport behavior. Compare the projection shader camera name in the exported USD with the camera_projection.camera parameter in the HDARNOLD_DEBUG_SCENE ass file; done means the shader uses the intended camera consistently.

Written by the indexing model from the issue text.