[TASK] Use cleaner check for MySQL fulltext in search

When activating mysql fulltext,
the DB tables "index_rel" and "index_words"
are not needed. This change makes
readability a lot easier, by avoiding
many unneeded checks.

Resolves: #102928
Releases: main
Change-Id: Id6080e00e4caf38d10d1115adda121e68b0cfe4a
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/82647


Reviewed-by: Jochen Roth <rothjochen@gmail.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Jochen Roth <rothjochen@gmail.com>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>