[FOLLOWUP] Remove remaining occurrences of JSImgCode

Resolves: #60523
Releases: 6.3
Change-Id: I38d9379277b173ba03c0761576ca60569b2bc88a
Reviewed-on: http://review.typo3.org/32736
Reviewed-by: Helmut Hummel <helmut.hummel@typo3.org>
Tested-by: Helmut Hummel <helmut.hummel@typo3.org>