fdo#82043: Instead of the bold font, use a higher multiplifier (4.3 backport)

Change-Id: I835e5c645ef52f23254178c782f2d484c5c0d20f
Reviewed-on: https://gerrit.libreoffice.org/11651
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>