Remove legacy code

[noemifrisina]

Closes #79

There are still some references to zlayer in the code which was used for fluorescence scans but is now legacy. This removes them, as well as the geobrick function in setup_beamline which was used for it.

To test:

• all references to zlayer have been removed
• tests pass

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 52.82%. Comparing base (fed9699) to head (663f101).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #85 +/- ## ========================================== + Coverage 51.61% 52.82% +1.21% ========================================== Files 23 23 Lines 3416 3311 -105 ========================================== - Hits 1763 1749 -14 + Misses 1653 1562 -91 ```

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