[BUGFIX] Fix search mode switcher of indexed_search

A wrong backport of #51189 broke the search mode switcher link of
indexed_search.
This patch corrects the wrong backport.

Resolves: #61982
Related: #51189
Releases: 6.1
Change-Id: Ie7427a67b56499c23ab6c049b71e5db7c21c933e
Reviewed-on: http://review.typo3.org/33081
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>