[TASK] Replace prophecy in EXT:form AbstractFinisherTest

Resolves: #98980
Releases: main
Change-Id: I82b58852b56da4336e639f32b2e8198c85751904
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76831


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