[BUGFIX] Make file paths absolute in GIFBUILDER

In CLI context the full path to the temporary generated file by the
GIFBUILDER can't be resolved. Because of this inconsistency, absolute
file paths are used from now on.

Resolves: #95379
Releases: master, 10.4
Change-Id: I6d2a489eee84843fc001ac405f69a15403598388
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/71335


Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Benni Mack <benni@typo3.org>