When implementing the setting for activity stream I added code to restart the application after flipping the setting - because I thought our code wouldn't be able to handle dynamically switching the panels. However it turns out that our code is absolutely capable of doing so. Let's remove the restart code.
It turns out that this works without restart on some devices (Nexus 9) but does not on others (Google Pixel XL). As this setting is only for developing/testing until the panel is ready to replace the top sites panel, let's just keep it the way it is.