Remove unused shoutbox channel state from side drawer

src/components/side_drawer/side_drawer.js

@@ -49,7 +49,6 @@ const SideDrawer = {
     currentUser () {
       return this.$store.state.users.currentUser
     },
-    shout () { return this.$store.state.shout.channel.state === 'joined' },
     unseenNotifications () {
       return unseenNotificationsFromStore(this.$store)
     },