[TASK] Cleanup Extbase for 6.1 release

* Remove whitespace after closing php tag
* Fix PhpDocComments

Releases: 6.1
Resolves: #47216
Change-Id: I8f35f9adb65c75cb11e1045bbade3d0b6708db86
Reviewed-on: https://review.typo3.org/19976
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring
Reviewed-by: Alexander Schnitzler
Tested-by: Alexander Schnitzler