fdo#74521: Only pick cell notes for that sheet, and skip the rest.

Change-Id: I06a069e835eb7f2f90d34f4fcdfd935aff0234de
(cherry picked from commit 771b9d2718f28beedbc1a913e8965cdd1fc75a88)
Reviewed-on: https://gerrit.libreoffice.org/7945
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>