Fixed randomly failing test

mysql-test/suite/perfschema/r/ortho_iter.result

 drop procedure if exists check_instrument;
+truncate table performance_schema.events_statements_summary_by_digest;
+flush status;
 create procedure check_instrument(in instr_name varchar(128))
 begin
 declare count_expected integer;

mysql-test/suite/perfschema/t/ortho_iter.test

@@ -9,6 +9,10 @@
 drop procedure if exists check_instrument;
 --enable_warnings
 
+# reset counters
+truncate table performance_schema.events_statements_summary_by_digest;
+flush status;
+
 delimiter $;
 create procedure check_instrument(in instr_name varchar(128))
 begin