[BUGFIX] Fix undefined key warning when opening record list

Access to array key $this->pageRow['editlock'] must be protected
with the neccessary fallback to false.

Resolves: #96343
Releases: main, 11.5
Change-Id: Ic181911709ba053e9c1f8b77d8b35684ba6c41c8
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72639


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