[TASK] Replace prophecy in EXT:form PropertyMappingConfigurationTest

Resolves: #98904
Releases: main
Change-Id: I659bad4926656c2d5e3ed3120a13ef8b14a720c9
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76330


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