This diff skipping sending new notif token requests to the bidirectional stream when the notifications are off by the `notifications.disable` config flag parameter. We don't need to send this message to the stream and should skip checking the existing notification token in this case.
Linear task: [[ https://linear.app/comm/issue/ENG-2639/disabling-notifications-handling-by-the-config-flag-in-tunnelbroker | ENG-2639 ]]