Thanks to the information in this discussion HP Envy 6055e scanner problems about a simple edit in the /etc/sane.d/dll.conf file, I was able to get my old scanner working very easily on the latest openSUSE Leap.
- Copy the firmware file ccd569.fw to /usr/share/sane/gt68xx
- In the file /etc/sane.d/dll.conf, uncomment the line containing gt68xx
After these two steps, the scanner was immediately ready for use.