Correct and reenable SmNodeToTextVisitor's test for RSUP

See 44a3a345ac2b9901122a9eac70538ef04417bbd4 about why ^ is chosen.

Change-Id: I05cda4d69eaa1757a95c06c199e09d9c67f47832
Reviewed-on: https://gerrit.libreoffice.org/13037
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>