Dubbo admin-0.5.0 消费者IP显示错误，全部显示为dubbo admin部署服务器IP地址

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

### Environment

* Dubbo Admin version: 0.5.0
* Registry center detail (type and version): zookeeper 3.4.6
* Operating System version: linux
* Java version: 1.8
* Dubbo version: 3.1.8/2.7.6

### Steps to reproduce this issue

1. dubbo服务端为3.1.8
2. dubbo消费端3.1.8和2.7.6共存
3. dubbo admin重启后首次看consumer信息内IP地址是对的。但是任意dubbo消费端重启后，dubbo admin内展示的consumer ip地址就全部变成了dubbo admin所在的部署服务器IP。

dubbo-registry-null-xxx.cache内看到很多无IP的consumer信息会被追加到对应provider后面：

consumer\:///com.xx.xx.lemma.api.provider.LemmaProvider?application\=web-xx-mobile&category\=consumers&check\=false&dubbo\=2.0.2&release\=2.7.6-SNAPSHOT consumer\:///com.xx.xx.lemma.api.provider.LemmaProvider?application\=service-baike&category\=consumers&check\=false&dubbo\=2.0.2&release\=2.7.6-SNAPSHOT consumer\:///com.xx.xx.lemma.api.provider.LemmaProvider?application\=service-xx-mix&category\=consumers&check\=false&dubbo\=2.0.2&release\=3.1.8

Reproduce with Dubbo Admin 0.5.0, ZooKeeper 3.4.6, and the mixed Dubbo 3.1.8/2.7.6 consumer setup described in the issue. Compare the consumer information before and after a consumer restart, and inspect the dubbo-registry-null-xxx.cache entries containing consumers without IPs. Done means the admin continues to display each consumer's actual IP after restarts.

Written by the indexing model from the issue text.