[!!!][TASK] Always throw exception if a userFunc does not exist

The parameter `$errorMode` is removed from the method
`GeneralUtility::callUserFunction()`. Thus, the checks agains this
variable are removed as well, causing exceptions being always thrown now.

Resolves: #74533
Releases: master
Change-Id: Ibf8b0c9de55b4d8d210dac8fc6c82b14ca7c849d
Reviewed-on: https://review.typo3.org/50996


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>