[BUGFIX] Respect multi-byte values in search sword

Resolves: #84857
Releases: master, 8.7
Change-Id: I72563fad6233f0508273f6a75b2f7ab51894e501
Reviewed-on: https://review.typo3.org/56795


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>