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/sp-vars.test

@@ -1015,7 +1015,9 @@ BEGIN
 END|
 delimiter ;|
 
+--disable_ps2_protocol
 SELECT f1('_aBcDe_');
+--enable_ps2_protocol
 
 SELECT * FROM t1;
 
@@ -1434,6 +1436,7 @@ end|
 create table t1 (a int)|
 insert into t1 (a) values (1), (2)|
 
+--disable_ps2_protocol
 set @b=1|
 set @a=0|
 select f1(), @b from t1|
@@ -1441,6 +1444,7 @@ select f1(), @b from t1|
 set @b:='test'|
 set @a=0|
 select f1(), @b from t1|
+--enable_ps2_protocol
 
 delimiter ;|