bugfix: fix bug of seata-server's metric

[robynron]

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

Ⅰ. Issue Description

seata-server侧定义的metrics常量，在发布metrics记录时，会存在tag覆盖的情况：

Ⅱ. Describe what happened

如上图所示，app_id是 “seata_springboot-app”的service，seata-server侧记录了其提交的5次全局事务的rollback记录。

紧接着，app_id是 “seata_springboot-app11”的service提交了1次rollback的全局事务，在seata-server侧则对相同的metric覆盖其之前的tag，并对metrics的value做了修改。

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

Just paste your stack trace here!

Ⅲ. Describe what you expected to happen

实际我们期望对每个服务，seata-server都会独立统计其metrics，而不出现tag与value覆盖的情况。

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

1. xxx
2. xxx
3. xxx

Ⅴ. Anything else we need to know?

Ⅵ. Environment:

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