[TASK] Mark various parts with phpdoc internal - part 3

All specific controllers for specific Backend actions, Backend-module related modules,
all hook implementations (where the core uses hooks by itself), and module-specific
ViewHelpers are now marked as @internal to ensure developers what is
part of the public TYPO3 Core API.

within
- EXT:indexed_search
- EXT:info
- EXT:linkvalidator
- EXT:lowlevel
- EXT:opendocs
- EXT:recordlist
- EXT:recycler
- EXT:redirects
- EXT:reports
- EXT:scheduler

All @api annotations have been removed.

Resolves: #86511
Releases: master
Change-Id: I80de460142266305c1af3ad437f939b7e4448676
Reviewed-on: https://review.typo3.org/58530


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>