fdo#74453: Only adjust tokens for top formula cells of formula group.

Change-Id: Id04387dffac271b3d617da0fbc19c862c929d60a
(cherry picked from commit 1556dbc451f067d8744378fb9bac0eaa7ef8f5ac)
Reviewed-on: https://gerrit.libreoffice.org/7946
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>