[AGIPD][CORRECT] Process all AGIPD trains if PPU device is missing or no trigger

Description

As discussed with @tmichela, this MR changes the PPU feature to process all trains if the specified device is missing or its last trigger is not part of the data collection.

This potentially dangerous on the online cluster, should there be a flag to disable it?

How Has This Been Tested?

in_folder = "/gpfs/exfel/exp/HED/202301/p003285/raw"
run = 328
use_ppu_device = 'HED_XTD6_PPU/MDL/PPU_TRIGGER'

Types of changes

• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Reviewers

@tmichela @ahmedk