Fix 500 error when creating mileston from group page

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/views/layouts/_init_auto_complete.html.haml

 - project = @target_project || @project
 - noteable_type = @noteable.class if @noteable.present?
+- if project
   :javascript
     GitLab.GfmAutoComplete.dataSource = "#{autocomplete_sources_namespace_project_path(project.namespace, project, type: noteable_type, type_id: params[:id])}"
     GitLab.GfmAutoComplete.cachedData = undefined;