[TASK] Cleanup docblocks for MySQLi-results

Resolves: #47341
Releases: 6.1
Change-Id: I0d6ba8903b98c1eb5ec19978e03ed78f1ef15638
Reviewed-on: https://review.typo3.org/20020
Reviewed-by: Jigal van Hemert
Tested-by: Jigal van Hemert
Reviewed-by: Dmitry Dulepov
Tested-by: Dmitry Dulepov