Add show_create param to toggle label creation option

app/views/shared/issuable/_label_dropdown.html.haml

+- show_create = local_assigns.fetch(:show_create, true)
 - extra_options = local_assigns.fetch(:extra_options, true)
 - filter_submit = local_assigns.fetch(:filter_submit, true)
 - show_footer = local_assigns.fetch(:show_footer, true)
@@ -18,8 +19,7 @@
       = h(multi_label_name(params[:label_name], "Label"))
     = icon('chevron-down')
   .dropdown-menu.dropdown-select.dropdown-menu-paging.dropdown-menu-labels.dropdown-menu-selectable
-    = render partial: "shared/issuable/label_page_default", locals: { title: "Filter by label" }
-    - if can? current_user, :admin_label, @project and @project
     = render partial: "shared/issuable/label_page_default", locals: { title: "Filter by label", show_footer: show_footer }
+    - if can? current_user, :admin_label, @project and @project and show_create
       = render partial: "shared/issuable/label_page_create"
     = dropdown_loading