[BUGFIX] Fix HMENU / LanguageMenuProcessor for translated pages

The method "getPagesOverlay" always returns the original
array even if the page was not translated.

The patch adds some tests and checks if the page
was actually overlaid.

Resolves: #96541
Related: #96492
Releases: main, 11.5
Change-Id: I942f3856d04fba1ae7bb58273f146e31bcc9bc64
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/73786


Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>