Update the large image save test and add several more.

[brugger1]

Description

I updated the large image save test in offscreensae.py after rebuilding mesagl on poodle that allows saving larger images than previously. I then added additional tests at larger image sizes including sizes that are too large that will automatically get scaled down so that they aren't too large.

Type of change

• [X] Other - Update tests

How Has This Been Tested?

I made the changes on the test system and ran the tests with --no-cleanup so that I could look at the images saved. They all looked correct and when I ran the offscreensave.py test it passed.

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Checklist:

• [X] 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.
• [X] I have added tests that prove my fix is effective or that my feature works.~~
• [X] 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.