[TASK] Remove unused prophecy in EXT:core TcaPreparationTest

Resolves: #98786
Releases: main
Change-Id: I66ffa0cd23323d593a5a0dee5d77e0e1c3da2cd8
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76712


Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Nikita Hovratov <nikita.h@live.de>
Reviewed-by: Nikita Hovratov <nikita.h@live.de>