Fix/DSSC DARK was missing from the new mapping modifications

Summary:

As we had old DSSC test data we missed this during our tests. Yesterday after adding new test data for DSSC. I tested dark and found this silly mistake that DSSC was missing from the new mapping additions.

Tests:

This was tested locally on the notebook and was hotpatched to max-exfl016 in the meantime to not block today's tests.

Report from production: http://max-exfl016:8008//gpfs/exfel/d/cal/caldb_store/xfel/reports/CALLAB/SCS_DET_DSSC1M-1/dark/dark_900113_r9982_210212_092238.pdf

Reviewers:

@danilevc @hammerd