Simplify code to display text of new notifications

We couldn't do this refactoring earlier because we weren't using the
unread notifications count. This was fixed in the previous commit.

app/components/layout/notification_item_component.rb

@@ -8,25 +8,17 @@ class Layout::NotificationItemComponent < ApplicationComponent
   private
 
     def text
-      if unread_notifications?
+      t("layouts.header.notification_item.new_notifications", count: unread_notifications.count)
-        t("layouts.header.notification_item.new_notifications", count: unread_notifications.count)
-      else
-        t("layouts.header.notification_item.no_notifications")
-      end
     end
 
     def notifications_class
-      if unread_notifications?
+      if unread_notifications.count > 0
         "unread-notifications"
       else
         "no-notifications"
       end
     end
 
-    def unread_notifications?
-      unread_notifications.count > 0
-    end
-
     def unread_notifications
       user.notifications.unread
     end

config/locales/en/general.yml

@@ -249,8 +249,8 @@ en:
         new_notifications:
           one: You have a new notification
           other: You have %{count} new notifications
+          zero: "You don't have new notifications"
         notifications: Notifications
-        no_notifications: "You don't have new notifications"
       sdg: "SDG"
   notifications:
     index:

config/locales/es/general.yml

@@ -249,8 +249,8 @@ es:
         new_notifications:
           one: Tienes una nueva notificación
           other: Tienes %{count} notificaciones nuevas
+          zero: "No tienes notificaciones nuevas"
         notifications: Notificaciones
-        no_notifications: "No tienes notificaciones nuevas"
       sdg: "ODS"
   notifications:
     index: