Pico shutdown should have a timeout configuration

[trentjeff]

See DefaultPicoServices.doShutdown().

            return es.submit(shutdown)
                    // note to self: have an appropriate timeout config for this
//                    .get(cfg.activationDeadlockDetectionTimeoutMillis(), TimeUnit.MILLISECONDS);
                    .get();

[trentjeff]

Most of this work apparently was already completed. Just putting some cleanup in #7051.