It seems that acat's #31575 (moved) patch disables all of this functionality. Specifically, with that patch in place ToolbarPanelHub.init() is not called, which means that the "What's New?" toolbar item and the app menu item are not visible.
acat, can you take a quick look and confirm that your #31575 (moved) patch disables the "What's New?" feature? If so, we can close this ticket and re-enable What's New if we decide to use it for onboarding.
Yes, by not initializing ActivityStream in AboutNewTab.jsm this should be disabled. The UI part seems to be implemented in ToolbarPanelHub.jsm and ToolbarBadgeHub.jsm, and that's only initialized in ASRouter.jsm, which will never run with our patch.