[BUGFIX] DebuggerUtility does not rewind instances of Iterator

Debugging a collection like ObjectStorage changes
the internal collection pointer which leads to the
collection being invalid.

Fixes: #43955
Releases: 6.1, 6.0, 4.7
Change-Id: I8258640c3ef7e2a7a4c53d608e673f59eecdeab1
Reviewed-on: https://review.typo3.org/17374
Reviewed-by: Stefan Froemken
Tested-by: Stefan Froemken
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Stefan Neufeind
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring