[BUGFIX] Remove non-existing "pseudo-site" logic

There are some leftovers where PseudoSite is mentioned.

Since TYPO3 v10.0 is built on Site Handling completely,
this logic is removed.

Resolves: #88625
Releases: master
Change-Id: I9f3b3a6c9a4bf29c2b509246c02d64aa5f536b4e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/61123


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Daniel Gorges <daniel.gorges@b13.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Daniel Gorges <daniel.gorges@b13.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>