SEATA 分布式事务模式问题

### Ⅰ. Issue Description

看官方文档，分布式事务支持AT,TCC和SAGA.

我看了seata-sample项目，貌似客户端口项目里面的application.yml文件没有地方指定到底是AT, TCC还是SAGA模式.

我的问题是，是不是在应用RM中用了@LocalTCC就是TCC模式，在应用中用了SAGA状态机器就是SAGA模式？不需要再application.yml里面显式指定分布式事务？

另一方面，我在script/client/spring/application.yml里面看到seata:data-source-proxy-mode: AT. 这个地方是可以指定事务模式吗？

但是我在project\seata-1.6.1\seata-spring-autoconfigure\seata-spring-autoconfigure-client\src\main\resources\META-INF\additional-spring-configuration-metadata.json这个文件里面又只看到支持AT和XA。对应的内容如下：

"hints": [
{
"name": "seata.data-source-proxy-mode",
"values": [
{
"value": "AT",
"description": "the default mode."
},
{
"value": "XA"
}
]
},

麻烦指导一下，如何配置才能使得应用是运行在AT,TCC还是SAGA模式下面？

### 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 :
- Seata version: 1.6
- OS :
- Others:

Read the Seata sample application.yml, script/client/spring/application.yml, and seata-spring-autoconfigure-client/src/main/resources/META-INF/additional-spring-configuration-metadata.json. Compare the documented AT, TCC, SAGA, XA, and @LocalTCC configuration references. Done means the documentation clearly explains how each transaction mode is selected and whether application.yml requires an explicit setting.

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