When the service.vgroupMapping is changed, the client will throw an exception

[pengten]

• [*] I have searched the issues of this repository and believe that this is not a duplicate.

Ⅰ. Issue Description

当 service.vgroupMapping 指向的集群在运行中被更改，client 访问 TC 的请求会被分散到多个集群中（包括被替换的旧集群）

When the cluster pointed to by service.vgroupMapping is changed during operation, the client's request to access the TC will be distributed among multiple clusters (including the replaced old cluster)

Ⅱ. Describe what happened

If there is an exception, please attach the exception trace:

Just paste your stack trace here!

Ⅲ. Describe what you expected to happen

Ⅳ. How to reproduce it (as minimally and precisely as possible)

1. 启动两个server
2. 运行client，vgroupMapping指向server1，
3. 运行中将vgroupMapping指向server2
4. 会发现client的请求被平分到server1和server2中

Ⅴ. Anything else we need to know?

Ⅵ. Environment:

• JDK version :
• Seata version: develop
• OS :
• Others: