Improve test/check_buildstock.rb

[joseph-robertson]

Pull Request Description

Closes #1051.

Checklist

Not all may apply:

• [ ] Tests (and test files) have been updated
• [ ] Documentation has been updated
• [ ] Changelog has been updated
• [ ] openstudio tasks.rb update_measures has been run
• [ ] No unexpected regression test changes on CI (checked comparison artifacts)