[BUGFIX] Invalid behaviour with GeneralUtility::trimExplode()

The subject's parts are wrongly trimmed although a limit is specified.
According to the PHP documentation, the values are trimmed for whitespace
in the end, not at the beginning.

Change-Id: Ifb4547b3349be2d31d5ce75b19db77eb6535d5ec
Resolves: #70864
Releases: master, 6.2
Reviewed-on: https://review.typo3.org/44178


Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Tested-by: Jigal van Hemert <jigal.van.hemert@typo3.org>