[TASK] Simplify API for checking link target

Previously, the function BrokenLinkRepository::getNumberOfBrokenLinks()
was used in the event listener. It is not necessary to return the count.
We now only check if the link target is in the list of broken links.

This makes the API easier to read and reduces the number of methods
with similar and misleading names.

Resolves: #90390
Releases: master
Change-Id: Ia94a7a0bd44bbc827864371f7c6694b4b8f8f52a
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63267


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>