civicrm_metatag_metatags_view_alter() should only act on CiviCRM pages

civicrm_metatag_metatags_view_alter() integrates with the Drupal Metatag contributed module. It's purpose is to ensure a CiviCRM page's <meta> tags include the query parameters.

At the moment this function operates on all pages when the Metatag module is enabled.

I've marked this bug as 'major' as it might have deleterious impacts on SEO etc.