Delete dead code after PRs 4512 and 4508

app/controllers/spree/admin/base_controller.rb

@@ -70,10 +70,6 @@ module Spree
         Spree.t(event_sym, resource: resource_desc)
       end
 
-      def render_js_for_destroy
-        render partial: '/spree/admin/shared/destroy'
-      end
-
       # Index request for JSON needs to pass a CSRF token in order to prevent JSON Hijacking
       def check_json_authenticity
         return unless request.format.js? || request.format.json?