Change jsduck macro to default to jsduck.json

Follows-up c00af9b99b0. The only effective change is in
unicode-jsduck which now uses jsduck.json instead of jsduck.config.json.

Update existing jobs to use jsduck-conf, thus effectively
remaining unchanged

Change-Id: Ifd650173d784a45252ac5fc78e39c9ffbc4c6bd4