[TASK] Refactor unit test to cover stdWrap_intval

Releases: master
Resolves: #76772
Change-Id: I88aa259704b615c8eb410252d7629d518a90d022
Reviewed-on: https://review.typo3.org/48677


Tested-by: Bamboo TYPO3com <info@typo3.com>
Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Susanne Moog <typo3@susannemoog.de>
Tested-by: Susanne Moog <typo3@susannemoog.de>