Improve transaction state detection logic

[wanggang1111111]

When DataSourceUtils.getConnection(this.dataSource) creates a new connection,
this connection is automatically registered with Spring's TransactionSynchronizationManager.
Therefore, DataSourceUtils.isConnectionTransactional() returns true,
but in reality, this connection is newly created and should not be considered as a Spring-managed transactional connection.

Use TransactionSynchronizationManager.isActualTransactionActive() to check if there is an active Spring transaction.
Only when an active transaction exists should the connection be considered as a Spring-managed transactional connection.

This approach correctly distinguishes between newly created connections and genuine Spring-managed transactional connections.

[hazendaz]

@wanggang1111111 Please add back the line you deleted and remove the liekly 'vim' command you stuck in that java doc.