fix copy&paste of conditional format between sheets

Change-Id: I8856bff376f0f6e366062eddbc68a9eee098be5b
Reviewed-on: https://gerrit.libreoffice.org/11327
Reviewed-by: Kohei Yoshida <libreoffice@kohei.us>
Tested-by: Kohei Yoshida <libreoffice@kohei.us>