LPS-43915 If there is no notificationHandler but we are sending it via email we should still deliver it so we can keep backwards compatibility for people using SubscriptionSender in his own portlets.
LPS-43915 Fix tests - If people are using SubscriptionSender in their own portlets, and they implement the notification framework (so they have a UserNotificationHandler), we shouldn't force them to implement subscriptions notification (so they may not have a UserNotificationDefinition) and it should still be sending email when the SubscriptionSender is used.
LPS-43915 Consistency between the previous 2 commits