Clean up script execution logic

[jeremystretch]

Proposed Changes

The logic currently in place for running custom scripts is in dire need of cleanup. Specifically, the internal _run_script() method relies on variables defined outside its scope, and needs to refactored/relocation.

Justification

Improvements in this area will make the code cleaner, easier to understand, and easier more maintainable long term.

[github-actions]

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[jeremystretch]

My initial concerns when raising this issue have generally been addressed by recent work.