LPS-42075 We should set the locale in the session only when the user is signed in. If the user is not signed in we shouldn't update the locale of the session because if we do it there is no way a guest user can switch the language using the language portlet (if he adds the locale in the url is fine because it doesn't go through the i18nFilter). For a signed in user we can set the locale in the session because when the user switches the language using the language portlet his preferred language is updated in his profile.