[BUGFIX] Fix typo in typo3/sysext/core/ext_tables.sql

The key should be named determineSiteRoot instead of determainSiteRoot.

Change-Id: Ia78832920ad73b76d712041e7546c578a6c4d50f
Resolves: #55534
Relates: #55180
Releases: 6.2
Reviewed-on: https://review.typo3.org/27213
Reviewed-by: Marcin Sągol
Tested-by: Marcin Sągol
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters