Extend CI testing

[chgio]

The current CI configuration only tests the sample script on sample model use case.
This is enough to check that the default container setup is working, but does not cover a bunch of stuff that's used in custom runs.

To be thorough, the CI job should test:

• sample script on sample model
• sample script on custom model
• custom script on sample model
• custom script on custom model

These functionalities (including) have all been confirmed (though manually and locally) as of v7.0.0-1, it would be nice to automate them for regression testing.