[JF][FXE] Replicate a raw dataset for legacy analysis code

Description

FXE has complained that a recent change in https://git.xfel.eu/detectors/pycalibration/-/merge_requests/735 broke their analysis code due to no longer copying over unchanged datasets, in this case data.trainId. Their code is using this JF-specific key instead of INDEX to align data.

Independent of the discussion on Zulip whether to treat these datasets differently, we should hotfix it for this week to not break their analysis code during operations.

How Has This Been Tested?

CALLAB reference run: p002478, r52

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Reviewers

@ahmedk