Address minor warnings and lint issues

[tpdownes]

A series of minor changes/fixes:

• De-capitalize error messages in line with guidance
• Remove a test func that has become unused

Submission Checklist

Please take the following actions before submitting this pull request.

• Fork your PR branch from the Toolkit "develop" branch (not main)
• Test all changes with pre-commit in a local branch #
• Confirm that "make tests" passes all tests
• Add or modify unit tests to cover code changes
• Ensure that unit test coverage remains above 80%
• Update all applicable documentation
• Follow Cloud HPC Toolkit Contribution guidelines #

[tpdownes]

I decided to remove one commit that is strictly necessary for #1467.