Fix errcheck issues in server/channels/app/platform/busy_test.go (#29318)

server/.golangci.yml

@@ -101,7 +101,6 @@ issues:
         channels/app/migrations.go|\
         channels/app/permissions.go|\
         channels/app/permissions_test.go|\
-        channels/app/platform/busy_test.go|\
         channels/app/platform/cluster_handlers.go|\
         channels/app/platform/config_test.go|\
         channels/app/platform/helper_test.go|\