Improved integration of automatic python tests with conda builds

Description

This MR improves the integration of the automatic python tests test_python_imports.py and test_python_scripts.py with conda builds, where they should hopefully now discover things properly, and report the results better. This required a bit of restructuring, but nothing major.

API Changes and Justification

Backwards Compatible Changes

• This change introduces no API changes
• This change adds new API calls

Backwards Incompatible Changes

• This change modifies an existing API
• This change removes an existing API

If any of the Backwards Incompatible check boxes are ticked please provide a justification why this change is necessary and why it needs to be done in a backwards incompatible way.

Review Status

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