[BUGFIX] Avoid notices while retrieving the cookie domain

Resolves: #99337
Releases: main, 11.5
Change-Id: Ia51d0328fc4abc19686375fd47770ead31eac53c
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77031


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