fixes 6.0 commit  9ae1e094
> PPTX export: correct position of rotated groups

However, there was nothing excluding the re-positioning
to only group items.

Change-Id: I62e36b46c0d2ac3e41f8d7d4ed82df11e6eb1ee5
Reviewed-on: https://gerrit.libreoffice.org/56386
Tested-by: Jenkins
Reviewed-by: Szymon Kłos <szymon.klos@collabora.com>