[BUGFIX] Indexed Search mysql takes section settings into account

Add section where clause to Indexed Search MySQL hook.
Before this patch, when using MySQL fulltext search, Indexed Search
returned results from all pages.
Now they are filtered taking correct section into account.

Releases: 7.6, master
Resolves: #45575
Change-Id: Ia5c2d2cbb2e866a4c4d56cc05ac97a85f491e6eb
Reviewed-on: https://review.typo3.org/45976


Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Frank Nägler <frank.naegler@typo3.org>
Tested-by: Frank Nägler <frank.naegler@typo3.org>