[EMSUSD-53] hitTest command fails when using VP2.0 render delegate

The hitTest command is returning an empty list rather than the expected cube model when running Pixar's automated test suite when using the VP2 Render Delegate. The failure occurs on [line 64 of the testBatchRendererIsolateSelection test](https://github.com/Autodesk/maya-usd/blob/ec6750b7b1311c474a857a0e78216c5dc16db93b/plugin/pxr/maya/lib/pxrUsdMayaGL/testenv/testBatchRendererIsolateSelection.py#L64). Please ignore the test name here - we are actually trying to test selection while using the VP2 renderer.

This test is part of a suite of tests that are run internally at Pixar. They are not included run as part of the external Pixar usdMaya plugin tests since they are making assumptions about the runtime environment that may not be valid for all users. However, moving forward, these tests should be run internally within Autodesk to validate correctness when testing any changes or fixes to the usdMaya plugin.

Start with plugin/pxr/maya/lib/pxrUsdMayaGL/testenv/testBatchRendererIsolateSelection.py at line 64 and reproduce the hitTest command under the VP2 Render Delegate. Trace why selection returns an empty list instead of the expected cube model; done means the internal automated test detects the cube while testing VP2 selection.

Written by the indexing model from the issue text.