dead code now since:
commit e7b460f919
Date: Sat Aug 30 15:23:11 2025 +0200
BitmapEx->Bitmap in canvas
now that Bitmap supports transparency
Change-Id: Ibc296ea82953e571390eea01628adfa71a4f6ab9
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/190517
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com>