- [x] I have searched the [issues](https://github.com/apache/incubator-dubbo/issues) of this repository and believe that this is not a duplicate.
- [x] I have checked the [FAQ](https://github.com/apache/incubator-dubbo/blob/master/FAQ.md) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo version: 2.7.0
* Operating System version: mac
* Java version: 1.8

### Steps to reproduce this issue

1.  `AbstractClient#initConnectStatusCheckCommand` set break point at `  !isConnected()`.
2. `AbstractClient#close()` set break point here.    
3.  start client first, start provider and then shutdown provider gracefully , let method `AbstractClient.close()` be executed. Then select step `1` and trigger the thread to execute `!isConnected`, here will always try to connect the offline machine.

Pls. provide [GitHub address] to reproduce this issue.

### Expected Result

What do you expected from the above steps？

When the server goes offline, the client will not reconnect the offline machine.

### Actual Result

What actually happens?

The client reconnects the offline machine every 2 seconds and causes a large number of arp packets(because ip is recycled and not available now).
URL overrideUrl = url;
                
                if (url.getParameter(CATEGORY_KEY) == null && OVERRIDE_PROTOCOL.equals(url.getProtocol())) {
                    overrideUrl = url.addParameter(CATEGORY_KEY, CONFIGURATORS_CATEGORY);
                }
                
                if (UrlUtils.isMatch(currentSubscribe, overrideUrl)) {
                    result.add(url);
                }
            }
            return result;
        }
    }
    private class ServiceConfigurationListener extends AbstractConfiguratorListener {
        private URL providerUrl;
        private OverrideListener notifyListener;
        public ServiceConfigurationListener(URL providerUrl, OverrideListener notifyListener) {
            this.providerUrl = providerUrl;
            this.notifyListener = notifyListener;
            this.initWith(providerUrl.getEncodedServiceKey() + CONFIGURATORS_SUFFIX);
        }
        private <T> URL overrideUrl(URL providerUrl) {
            return RegistryProtocol.getConfigedInvokerUrl(configurators, providerUrl);
        }
        @Override
        protected void notifyOverrides() {
            notifyListener.doOverrideIfNecessary();
        }
    }
    private class ProviderConfigurationListener extends AbstractConfiguratorListener {