[TASK] Avoid obsolete trim() in RelationHandler

There is no point to trim() value arrays that have
been created with GU::trimExplode() just the line
before. Clean up the loop a bit along the way.

Resolves: #103674
Releases: main
Change-Id: Ia5580b292b1a44a0291468b35bc1e5ca5b2f9823
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/83928


Tested-by: core-ci <typo3@b13.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Andreas Kienast <a.fernandez@scripting-base.de>
Tested-by: Andreas Kienast <a.fernandez@scripting-base.de>