[TASK] Replace prophecy in ExtensionManagementServiceTest

Note, that this patch also fixes some useless prophecy
`->willReturn()` calls, which did not test something. Actually,
it should have been checked, if the affected methods have been
called with the given arguments.

Resolves: #98975
Releases: main
Change-Id: Iff326ed1e3211fb76078b758d4a3f58d5e353a03
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76915


Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>