[TASK] Deprecate $TSFE->anchorPrefix

The shortcut variable for having the anchorPrefix within
$TSFE is set when a baseURL is defined and does the same
as config.prefixLocalAnchors = auto. It is solely used for
Indexed Search and only if baseURL is activated.

The patch deprecates this property and implements
the functionality directly when needed within indexed_search.

Resolves: #65938
Releases: master
Change-Id: Ie57f57501f15f69ef5f6859d0517f7c0bcced117
Reviewed-on: http://review.typo3.org/38040


Reviewed-by: Jan Helke <typo3@helke.de>
Tested-by: Jan Helke <typo3@helke.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>