Bug #104250 kill query will case some mysql client block

Description:
at sometimes the kill query will case some mysql client block.

conn1 (use mysql client) to execut a muilt-statment;
conn2 (use mysql client) kill query conn1;
the conn1 may block for read mysqld response.

The conn1 block reason is that the kill query happen at the muilt-statment one statement have finsh and the next statement not start, the packet response to the
client have finsh with ok and SERVER_MORE_RESULTS_EXISTS status also in the packet. And at the THD::send_kill_message() the get_stmt_da()->is_set() will be true, so the packet with ok and SERVER_MORE_RESULTS_EXISTS will response to the client, but this query is interrupt, no more messages will be responsed. But the client will wait next response message.

How to repeat:
1.add this code at sql_parse.cc:1856 before the 'while (!thd->killed && (parser_state.m_lip.found_semicolon != nullptr) &&'
    
```
      DBUG_EXECUTE_IF("test_muilt_statement_error", {
        thd->killed = THD::KILL_QUERY;
      });
``` 
2.make with the debug and make install

3.use the mysql to login;
mysql> create database test;
Query OK, 1 row affected (0.14 sec)

mysql> use test;
Database changed

mysql> create table t1(c1 int, c2 int);
Query OK, 0 rows affected (0.09 sec)

mysql> SET @@session.debug="+d,test_muilt_statement_error";
Query OK, 0 rows affected (0.00 sec)

mysql> delimiter //
mysql> insert into t1 values(1, 1);
    -> insert into t1 values(2, 2);
    -> //
Query OK, 1 row affected (0.02 sec)
....block

Hello deng yl,

Thank you for the report and test case.

regards,
Umesh