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/range_vs_index_merge.test

@@ -698,6 +698,7 @@ DROP INDEX CityName on City;
 CREATE INDEX Name ON City(Name);
 CREATE INDEX Population ON City(Population);
 
+--disable_ps2_protocol
 --disable_view_protocol
 --replace_column 9 #
 EXPLAIN 
@@ -759,6 +760,7 @@ SELECT * FROM City
 ORDER BY Population LIMIT 5;
 SHOW STATUS LIKE 'Handler_read_%';
 --enable_view_protocol
+--enable_ps2_protocol
 
 set optimizer_switch=@save_optimizer_switch;