Ensure coverage with tests of all workflow configurations

[ekatef]

It appears that some configuration of the workflow are not captured by CI.

For example, recent bugs in augmented_line_connections have been obvious with run_tests but were not found by CI, as reported by @finozzifa when working on #1011 and #1013.

Currently augmentation is not used in the tutorial:

https://github.com/pypsa-meets-earth/pypsa-earth/blob/3f3a32ffebcdf9b8ebd1c3a39a0b508c1298a0f1/config.tutorial.yaml#L63-L64

But it's switched-on in custom.config which should be used to build a test configuration:

https://github.com/pypsa-meets-earth/pypsa-earth/blob/3f3a32ffebcdf9b8ebd1c3a39a0b508c1298a0f1/test/config.custom.yaml#L19-L20

Describe the feature you'd like to see

Would be great to ensure that CI runs all the rules.

[ekatef]

As a comment, it would be also great to use both AC and DC representations in CI tests. Although, DC part is a bit tricky as it requires adding new data to the tutorial.

[ekatef]

We still have a number of testing related issues which may be related to this one. In particular, #625 and #715 can be relevant.