[TASK] Remove extbase Request controllerSubpackageKey

setControllerSubpackageKey(), getControllerSubpackageKey()
and property controllerSubpackageKey of extbase Request
are essentially an artifact from flow and unused in
v11 core. The information is only carried around at
one place but never actively used. This @internal
handling is dropped with the patch.

Change-Id: I546645b58cab351bac408e5772400f9cfe5d7b03
Resolves: #94326
Related: #86521
Releases: master
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/69469


Tested-by: core-ci <typo3@b13.com>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Benni Mack <benni@typo3.org>