[TASK] Fix deprecation warning in idnaEncode

__METHOD__ already includes the class name so __CLASS__ has to be
removed.

Resolves: #88679
Releases: master
Change-Id: I9a5fb6a4622a811f18547b55b22fdde0ea4ad62c
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/61219


Tested-by: Alexander Schnitzler <review.typo3.org@alexanderschnitzler.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Alexander Schnitzler <review.typo3.org@alexanderschnitzler.de>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>