[TASK] Refactor unit test to cover stdWrap_strtotime

Releases: master
Resolves: #76778
Change-Id: I423179814acd3d8a43b8b790ba7c34e0c8706616
Reviewed-on: https://review.typo3.org/48686


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