feature: global lock retry when autocommit=false

## Why you need it?
Is your feature request related to a problem? Please describe in details
English: When a connection is set to autocommit=false, the branch transaction cannot be retried if a global lock conflict occurs.

Chinese: 当连接设置为autocommit = false时，如果发生全局锁定冲突，则无法重试分支事务。

## How it could be?
A clear and concise description of what you want to happen. You can explain more about input of the feature, and output of it.

## Other related information
Add any other context or screenshots about the feature request here.

The issue names Seata branch transactions, global lock conflicts, and autocommit=false, but provides no files, tests, or entry points. Start by locating the Java code that handles branch transaction retries and global lock conflicts, then clarify the expected retry behavior and define tests covering autocommit=false before implementation.

Written by the indexing model from the issue text.