Update some rendering/volume_rect_singleDomain mode specific baselines.

[brugger1]

Description

I updated a couple of mode specific baselines from rendering/volume_rect_singleDomain.py that had a few imperceptible pixel differences.

Type of change

• [X] Other - Update test suite baseline images

How Has This Been Tested?

I copied the test results directly from last nights test suite run. I verified that the new images looked as expected.

Reminders:

• Please follow the style guidelines of this project.
• Please perform a self-review of your code before submitting a PR and asking others to review it.
• Please assign reviewers (see VisIt's PR procedures for more information).

Checklist:

• [ ] I have commented my code where applicable.
• [ ] I have updated the release notes.
• [ ] I have made corresponding changes to the documentation.
• [ ] I have added debugging support to my changes.
• [ ] I have added tests that prove my fix is effective or that my feature works.
• [ ] I have confirmed new and existing unit tests pass locally with my changes.
• [ ] I have added new baselines for any new tests to the repo.
• [ ] I have NOT made any changes to protocol or public interfaces in an RC branch.