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

### Environment

* Dubbo version: 2.7.3
* Operating System version: Mac OS
* Java version: 1.8

### Steps to reproduce this issue

1.RouterChain#buildChain(URL)
2.RouterChain#initWithRouters()
3.RouterChain#sort()


### Expected Result

ServiceRouter is High priority than AppRouter

### Actual Result

AppRouter is High priority than ServiceRouter

### Cause by
the code was on ListenableRouter 94~96 line
```
public abstract class ListenableRouter extends AbstractRouter implements ConfigurationListener {    
    ......
    ......
    @Override
    public int getPriority() {
        return DEFAULT_PRIORITY;
    }
```
### Resolve
i think can like this：
```
public abstract class ListenableRouter extends AbstractRouter implements ConfigurationListener {    
    ......
    ......
    @Override
    public int getPriority() {
        return priority;
    }
```
import org.apache.dubbo.common.logger.LoggerFactory;
import org.apache.dubbo.common.utils.CollectionUtils;
import org.apache.dubbo.common.utils.StringUtils;
import org.apache.dubbo.rpc.Invocation;
import org.apache.dubbo.rpc.Invoker;
import org.apache.dubbo.rpc.RpcException;
import org.apache.dubbo.rpc.cluster.Router;
import org.apache.dubbo.rpc.cluster.router.AbstractRouter;
import org.apache.dubbo.rpc.cluster.router.condition.ConditionRouter;
import org.apache.dubbo.rpc.cluster.router.condition.config.model.ConditionRouterRule;
import org.apache.dubbo.rpc.cluster.router.condition.config.model.ConditionRuleParser;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;
/**
 * Abstract router which listens to dynamic configuration
 */
public abstract class ListenableRouter extends AbstractRouter implements ConfigurationListener {
    public static final String NAME = "LISTENABLE_ROUTER";
    private static final String RULE_SUFFIX = ".condition-router";
    private static final Logger logger = LoggerFactory.getLogger(ListenableRouter.class);
    private ConditionRouterRule routerRule;
    private List<ConditionRouter> conditionRouters = Collections.emptyList();
    public ListenableRouter(URL url, String ruleKey) {
        super(url);
        this.force = false;
        this.init(ruleKey);
    }
    @Override
    public synchronized void process(ConfigChangedEvent event) {