Replace the dynamic property on SpecialTrackingCategories object,
this was used to store preloaded Category objects.
Dynamic properties are deprecated in php8.2
The preload and storage is now done with the service.
Adjust doc to LinkTarget (Id0cc2ca)
Bug: T324897
Change-Id: I891ad79bc357d32585ef4d9206d398c5a75222aa
(cherry picked from commit 9d98cc1ae6)
