Test cyclical price calculation with more complex cycles

We should add a regression test containing a cycle with more than 2 nodes. Easiest approach would be to just add one or more extra flows to the existing `circularity` example (e.g. gas extraction requires electricity).

A problem with this currently is that most complex cycles fail due to limitations with the investment algorithm (discussed in #1089).

A couple of approaches:
- run the model only for the first year, as no investments take place in the first year
- wait until we fix the issues with investments