[TASK] Remove the "@todo define visibility" in ext:indexed_search

The "@todo Define visibility" is not very helpful because:

 * Nobody knows what breaks if changing the visibility
 * The code is flooded with todos which makes it hard
   to work with in an IDE

During ACME it was decided to remove the @todo again.

Resolves: #62176
Related: #61957
Releases: master
Change-Id: I3aa54c1fa0f8fbe662b1c5609a7fe6a5747c9d6a
Reviewed-on: http://review.typo3.org/33272
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>