Webform advanced feature to index forms should be replace by view mode.

Webform contains a site-wide administrative option to determine whether to index webfrom form components, called "Include webform forms in search index". This option should be replaced by the Drupal 7 way of handling this -- reliance on the fields placed in the Search Index view mode.

#1919872: Skip hook_node_view() if Webform is not rendering a form for a view mode introduced the change to actually honor view modes. This issue removes the administrative option and code that references it.