Use Apache content negotiation in centos-noindex
    
    - Previously, both centos-indexhtml and centos-noindex were using the
      same file structure, which involves a javascript redirection in order
      to show localized content. However, doing so for Apache HTTP test page
      is an unnecessary burden if you want to preserve the behaviour of
      showing the test page in the main domain (without any further slashes
      in the URL or visible redirections) when no index.html is at
      /var/www/html/ directory. So, centos-noindex changed the layout to use
      Apache content negotiation instead, based on the languages we are
      providing localization for.
    
      To implement this, the welcome.conf file in httpd package should look
      like the following:
    
          <LocationMatch "^/+$">
            Options -Indexes
            ErrorDocument 403 /noindex/index.html
          </LocationMatch>
    
          Alias /noindex /usr/share/httpd/noindex
    
          <Directory /usr/share/httpd/noindex>
            Options MultiViews
            DirectoryIndex index.html
    
            AddLanguage en-US .en-US
            AddLanguage es-ES .es-ES
            AddLanguage zh-CN .zh-CN
            AddLanguage zh-HK .zh-HK
            AddLanguage zh-TW .zh-TW
    
            LanguagePriority en-US
            ForceLanguagePriority Fallback
    
            AllowOverride None
            Require all granted
          </Directory>
    
    - centos-*/Makefiles were updated to reflect centos-noindex structural
      changes.
    
    - Localization actions were moved from html/centos-*/Makefile to
      html/Makefile.