Tidy up "Remove fork relationship" of project edit

This section of the project edit page is moved to a separate HAML view
in anticipation of a refactor

app/views/projects/_remove_fork.html.haml

+- return unless @project.forked? && can?(current_user, :remove_fork_project, @project)
+
+.sub-section
+  %h4.danger-title= _('Remove fork relationship')
+  %p= remove_fork_project_description_message(@project)
+
+  = form_for @project, url: remove_fork_project_path(@project), method: :delete, remote: true, html: { class: 'transfer-project' } do |f|
+    %p
+      %strong= _('Once removed, the fork relationship cannot be restored and you will no longer be able to send merge requests to the source.')
+    = button_to _('Remove fork relationship'), '#', class: "gl-button btn btn-danger js-confirm-danger", data: { "confirm-danger-message" => remove_fork_project_warning_message(@project) }

app/views/projects/edit.html.haml

@@ -109,15 +109,7 @@
               %li= _('Project visibility level will be changed to match namespace rules when transferring to a group.')
           = f.submit 'Transfer project', class: "gl-button btn btn-danger js-confirm-danger qa-transfer-button", data: { "confirm-danger-message" => transfer_project_message(@project) }
 
-    - if @project.forked? && can?(current_user, :remove_fork_project, @project)
-      .sub-section
-        %h4.danger-title= _('Remove fork relationship')
-        %p= remove_fork_project_description_message(@project)
-
-        = form_for @project, url: remove_fork_project_path(@project), method: :delete, remote: true, html: { class: 'transfer-project' } do |f|
-          %p
-            %strong= _('Once removed, the fork relationship cannot be restored and you will no longer be able to send merge requests to the source.')
-          = button_to _('Remove fork relationship'), '#', class: "gl-button btn btn-danger js-confirm-danger", data: { "confirm-danger-message" => remove_fork_project_warning_message(@project) }
+    = render 'remove_fork', project: @project
 
     = render 'remove', project: @project