[BUGFIX] rdndt getClassSchema() in thawProperties(

getClassSchema() is being called within a foreach loop while the
$className never changes for that call.

Change-Id: I699a1a0ab34d784b7463244f218f4e8a0c0b7a0c
Resolves: #55991
Releases: 6.2
Reviewed-on: https://review.typo3.org/27633
Reviewed-by: Marcin Sągol
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel