[BUGFIX] Ensure type safety for ViewHelper calling ImageService

The ImageService::getImage requires a string as first and a boolean as
third parameter. The ThumbnailViewHelper must respect this requirement.

Resolves: #87621
Relates: #87599
Releases: master
Change-Id: Ib84f88665fd692629efdb54a33ff83263abe6bfe
Reviewed-on: https://review.typo3.org/59617


Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Mona Muzaffar <mona.muzaffar@gmx.de>
Tested-by: Mona Muzaffar <mona.muzaffar@gmx.de>
Tested-by: TYPO3com <noreply@typo3.com>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>