refs #703: preserve read-only transaction for Text2SQL

vpd-backoffice/src/main/java/com/cloudhandson/vpdbackoffice/service/SmilegateSelectAiService.java

@@ -127,6 +127,7 @@ public class SmilegateSelectAiService {
     try (Connection connection = DriverManager.getConnection(
         selectAi.dbUrl(), selectAi.dbUsername(), selectAi.dbPassword());
          Statement transaction = connection.createStatement()) {
+      connection.setAutoCommit(false);
       connection.setReadOnly(true);
       transaction.execute("SET TRANSACTION READ ONLY");
       try (PreparedStatement statement = connection.prepareStatement(generatedSql)) {