[TASK] Replace prophecy in EXT:backend/*/Unit/*/FormDataCompilerTest.php

Resolves: #98829
Releases: main
Change-Id: Ica7171dd9cfd4045d8f712315178f745ffeb16b8
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76437


Tested-by: core-ci <typo3@b13.com>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>