fix: Extend the locale without variant check for article locales as well (#11021)

We allow users to select locale variants when creating the help center
(e.g., pt_BR or en_UK). However, the selected variant may not always be
available for translation in the app. In such cases, we need to fall
back to either the base language or the default locale.

While this fallback logic was implemented for the portal locale, it was
missing for article locales.

This PR fixes that issue.

app/controllers/public/api/v1/portals/base_controller.rb

@@ -1,4 +1,6 @@
 class Public::Api::V1::Portals::BaseController < PublicController
+  include SwitchLocale
+
   before_action :show_plain_layout
   before_action :set_color_scheme
   before_action :set_global_config
@@ -27,14 +29,7 @@ class Public::Api::V1::Portals::BaseController < PublicController
   end
 
   def switch_locale_with_portal(&)
-    locale_without_variant = params[:locale].split('_')[0]
-    is_locale_available = I18n.available_locales.map(&:to_s).include?(params[:locale])
-    is_locale_variant_available = I18n.available_locales.map(&:to_s).include?(locale_without_variant)
-    if is_locale_available
-      @locale = params[:locale]
-    elsif is_locale_variant_available
-      @locale = locale_without_variant
-    end
+    @locale = validate_and_get_locale(params[:locale])
 
     I18n.with_locale(@locale, &)
   end
@@ -44,12 +39,12 @@ class Public::Api::V1::Portals::BaseController < PublicController
     Rails.logger.info "Article: not found for slug: #{params[:article_slug]}"
     render_404 && return if article.blank?
 
-    @locale = if article.category.present?
-                article.category.locale
-              else
-                article.portal.default_locale
-              end
-
+    article_locale = if article.category.present?
+                       article.category.locale
+                     else
+                       article.portal.default_locale
+                     end
+    @locale = validate_and_get_locale(article_locale)
     I18n.with_locale(@locale, &)
   end