Usd file with an ArnoldUsd node that loads

**Describe the bug**
An ArnoldUsd node that loads a usd file with other ArnoldUsd nodes crashes the host application.
I crashed Maya, Houdini, and 3ds Max (using the latest release plugins for Arnold 6.2.1.1)

kicking a usd file didn't crash.

chrome-spheres.usda has three ArnoldUsd nodes. They each load chrome-sphere.usda.
[chrome-spheres.usda.txt](https://github.com/Autodesk/arnold-usd/files/6977606/chrome-spheres.usda.txt)
[chrome-sphere.usda.txt](https://github.com/Autodesk/arnold-usd/files/6977617/chrome-sphere.usda.txt)

Scene file that you can kick (it didn't crash for me).
[nested-ArnoldUsd-nodes.usda.txt](https://github.com/Autodesk/arnold-usd/files/6977638/nested-ArnoldUsd-nodes.usda.txt)

**To Reproduce**
1. In Maya, create an aiStandin and load the attached chrome-spheres.usda file. Maya crashes and sends a CER report (I submitted 310222060, 310221421, 310222102, and 310220645).

**Used Software Versions**
- Arnold: 6.2.1.1
- OS: Windows 10
- Any 3rd-party app: Maya 2022.1, 3ds Max 2022, Houdini 18.5

**Additional context**
Add any other context about the problem here.

Start by reproducing the crash in Maya with the attached chrome-spheres.usda and chrome-sphere.usda files, then compare it with nested-ArnoldUsd-nodes.usda, which reportedly does not crash. Check whether loading nested ArnoldUsd nodes consistently crashes Maya, Houdini, or 3ds Max, and consider the issue done when the supplied nested scene loads without crashing.

Written by the indexing model from the issue text.