FailureHandler重写无法实现回滚失败处理

- [ ] I have searched the [issues](https://github.com/seata/seata/issues) of this repository and believe that this is not a duplicate.

### Ⅰ. Issue Description
单机模拟镜像不一致导致回滚失败处理问题。TM端捕获的异常是feign远程调用出的错（不过不就是分支事务处理失败所以触发回滚吗），导致捕获的异常状态始终是 RollbackDone就结束了，不会走自实现的FailureHandler。此外好奇的是分支事务的处理不是直接响应给TC吗？

### 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. xxx
2. xxx
3. xxx

### Ⅴ. Anything else we need to know?

### Ⅵ. Environment:

- JDK version : 11
- Seata version: 1.6.0
- OS : Win10
- Others: