Firefox API does not allow to control any of these options, they are either firefox global options (which I could not find), or system-wide options for notifications.

Another user suggested disabling the notifications, would that work for you? (personally I don't like it that much because in bad connections the link creation is not immediate)

edit: link to API description https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/notifications/NotificationOptions