[TASK] Deprecate AbstractService

Class TYPO3\CMS\Core\Service\AbstractService as part of
an ancient 'services' API has been rendered unused in
core with #88646. To further streamline the authentication
API and related helper methods, this class is marked
deprecated now.

This shouldn't have much impact for extensions in the
wild, since the API never found many usages apart from
core authentication related concerns.

Resolves: #94313
Related: #88646
Releases: master
Change-Id: I79e303937320f28667814644964acc4aeebd091e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/69461


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>