GlobalTransactionScanner 多例bean问题

- [ ] 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
在sprigboot中对注解的目标类进行代理时，为啥需要判断PROXYED_SET，如果是多例bean，每次都返回的都是原始对象，而非代理对象

Start by tracing the Spring Boot annotation-target proxying logic around PROXYED_SET and reproduce the reported behavior with a multi-instance bean. Review the issue discussion and determine whether each bean lookup should return a proxy rather than the raw object; done requires an agreed behavior and a regression test for multi-instance beans.

Written by the indexing model from the issue text.