[AGIPD][FF] Styling modification for both FF notebooks:1st nb cell, and removing uneeded imports

Description

This is a small MR for removing/modifying 1st nb cell in the main FF notebook and the summary notebook.

The main drive behind this MR is to correct h5path_ctrl as this has already been changed in the summary notebook to ctrl_source_template with a value fit for Extra-data.

There has been as well a cleanup of the unneeded imports.

How Has This Been Tested?

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Types of changes

• Style (formatting changes only, no code changes)

Checklist:

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