问题描述：发现服务关停过程中未正常调用ServiceDiscovery的unregister方法

问题原因：
1. preDestroy中，先执行destroyRegistries()，再执行destroyServiceDiscoveries()，最后执行unregisterServiceInstance()
~~~
    @Override
    public void preDestroy() {
        synchronized (destroyLock) {
            if (isStopping() || isStopped()) {
                return;
            }
            onStopping();

            destroyRegistries();
            destroyServiceDiscoveries();
            destroyMetadataReports();

            unRegisterShutdownHook();
            if (asyncMetadataFuture != null) {
                asyncMetadataFuture.cancel(true);
            }
            unregisterServiceInstance();
        }
    }
~~~
2. destroyRegistries()方法中调用destroyAll()方法，将容器registries中所有Registry进行销毁并从容器registries中移除，此时容器registries中已经没有数据，并且所有与注册中心的通信工具（如nacos的NamingService，zk的CuratorFramework）都被销毁
~~~
   public void destroyAll() {
        if (!destroyed.compareAndSet(false, true)) {
            return;
        }

        if (LOGGER.isInfoEnabled()) {
            LOGGER.info("Close all registries " + getRegistries());
        }
        // Lock up the registry shutdown process
        lock.lock();
        try {
            for (Registry registry : getRegistries()) {
                try {
                    registry.destroy();
                } catch (Throwable e) {
                    LOGGER.warn(e.getMessage(), e);
                }
            }
            registries.clear();
        } finally {
            // Release the lock
            lock.unlock();
        }
    }
~~~
3. destroyServiceDiscoveries()、unregisterServiceInstance()执行时，已经无法从容器registries中获取ServiceDiscoveries（即使能获取到，与注册中心的通信工具NamingService\CuratorFramework等已经被销毁无法使用）

修改方法：将unregisterServiceInstance()调整到destroyRegistries()之前，并删除destroyServiceDiscoveries()
~~~
   @Override
    public void preDestroy() {
        synchronized (destroyLock) {
            if (isStopping() || isStopped()) {
                return;
            }
            onStopping();
            
            unregisterServiceInstance();
            destroyRegistries();
            destroyMetadataReports();

            unRegisterShutdownHook();
            if (asyncMetadataFuture != null) {
                asyncMetadataFuture.cancel(true);
            }

        }
    }
~~~

}
    }
    private boolean isUsedRegistryAsConfigCenter(RegistryConfig registryConfig) {
        return isUsedRegistryAsCenter(registryConfig, registryConfig::getUseAsConfigCenter, "config",
            DynamicConfigurationFactory.class);
    }
    private ConfigCenterConfig registryAsConfigCenter(RegistryConfig registryConfig) {
        String protocol = registryConfig.getProtocol();
        Integer port = registryConfig.getPort();
        URL url = URL.valueOf(registryConfig.getAddress(), registryConfig.getScopeModel());
        String id = "config-center-" + protocol + "-" + url.getHost() + "-" + port;
        ConfigCenterConfig cc = new ConfigCenterConfig();
        cc.setId(id);
        cc.setScopeModel(applicationModel);
        if (cc.getParameters() == null) {
            cc.setParameters(new HashMap<>());
        }
        if (CollectionUtils.isNotEmptyMap(registryConfig.getParameters())) {
            cc.getParameters().putAll(registryConfig.getParameters()); 
        }
        cc.getParameters().put(CLIENT_KEY, registryConfig.getClient());
        cc.setProtocol(protocol);
        cc.setPort(port);
        if (StringUtils.isNotEmpty(registryConfig.getGroup())) {
            cc.setGroup(registryConfig.getGroup());
        }
        cc.setAddress(getRegistryCompatibleAddress(registryConfig));
        cc.setNamespace(registryConfig.getGroup());
        cc.setUsername(registryConfig.getUsername());
        cc.setPassword(registryConfig.getPassword());