[BUGIFX] RTEmagic upgrade wizard: missing attributes

When the RTE creates a magic images it uses data-* attributes
to keep a reference to the original FAL record. The upgrade
wizard migrates the images, creates the sys_file entries but
does not add the data-* attributes.

Resolves: #49733
Releases: 6.1, 6.2
Change-Id: Ib483355336d1331892920ada847850a61c35a3af
Reviewed-on: https://review.typo3.org/22285
Reviewed-by: Francois Suter
Tested-by: Francois Suter