fix negative error bar range export, fdo#75510

Change-Id: Icca2f9fc26b15b968a940e5c73f7ad3781f75e94
(cherry picked from commit 7470b3ef17570581fe590a4853de59cac1be6ea5)
Reviewed-on: https://gerrit.libreoffice.org/8536
Reviewed-by: Kohei Yoshida <libreoffice@kohei.us>
Tested-by: Kohei Yoshida <libreoffice@kohei.us>