Fix failing raytracing unit test

[GernotMaier]

Unclear why this worked before - setting caplog.at_level(logging.INFO) uses the correct logging level.

Further minor changes:

• remove a spurious debug print out in a test
• slightly rearrange the check for KeyError in raytraing:plot (asking for forgiveness..)

[VictorBarbosaMartins]

All good. I also have not figured out why the the level of caplog was changed, as it is supposed to be always come back to its original state when the with statement ends.

[GernotMaier]

OK, thanks for the review!!