[DSSC][Dark] Remove unused instrument parameter from DSSC dark notebook
Description
This little MR removes an unused instrument parameter from the DSSC Dark notebook.
This makes no functional changes to the detector, but reduces confusion for DSSC report readers.
How Has This Been Tested?
This was tested locally by running the notebook and seeing it finish correctly.
Relevant Documents (optional)
Closes #67 .
Types of changes
- Chore (non-code changes, e.g. comments, readme, grammar, etc...)
Checklist:
- My code follows the code style of this project.