[DOCS] Fix code example in comment of UserSessionManager

Resolves: #102706
Releases: main, 12.4
Change-Id: Ia250046ca8e36a82012555a8ed4e638e3746c787
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/82265


Tested-by: Garvin Hicking <gh@faktor-e.de>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Garvin Hicking <gh@faktor-e.de>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>