MDEV-31003: Second execution for ps-protocol

This patch adds for "--ps-protocol" second execution
of queries "SELECT".
Also in this patch it is added ability to disable/enable
(--disable_ps2_protocol/--enable_ps2_protocol) second
execution for "--ps-prototocol" in testcases.

mysql-test/main/join.test

@@ -659,7 +659,9 @@ create table t3 (a int not null, primary key(a));
 insert into t3 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
 
 flush status;
+--disable_ps2_protocol
 select * from t1, t2, t3 where t3.a=t1.a and t2.a=t1.b;
+--enable_ps2_protocol
 explain select * from t1, t2, t3 where t3.a=t1.a and t2.a=t1.b;
 --echo We expect rnd_next=5, and read_key must be 0 because of short-cutting:
 show status like 'Handler_read%'; 
@@ -958,7 +960,9 @@ INSERT INTO t1 VALUES (3,'b'),(4,NULL),(5,'c'),(6,'cc'),(7,'d'),
 INSERT INTO t2 VALUES (2,NULL);
 ANALYZE TABLE t1,t2;
 FLUSH STATUS;
+--disable_ps2_protocol
 SELECT * FROM t1 JOIN t2 ON t1.v = t2.v WHERE t2.v IS NULL ORDER BY 1;
+--enable_ps2_protocol
 SHOW STATUS LIKE 'Handler_read_%';
 DROP TABLE t1, t2;