`cld_steer.py` incompatible with geometries pre `CLD_o2_v07`

This is due to us now using the non-cylindrical tracking region that does not exists for the older geometries.

I don't have any idea for a good solution though :(

Start with cld_steer.py and compare how it accesses the non-cylindrical tracking region with the geometry definitions available before CLD_o2_v07. Reproduce the failure using an older geometry, then determine a compatible behavior for those geometries and verify that newer geometries continue to work.

Written by the indexing model from the issue text.