MDEV-31877: ASAN errors in Exec_time_tracker::get_cycles with innodb slow log verbosity

Remove redundant delete_explain_query() calls in

sp_instr_set::exec_core(), sp_instr_set_row_field::exec_core(),
sp_instr_set_row_field_by_name::exec_core().

These calls are made before the SP instruction's tables are
"closed" by close_thread_tables() call.

When we call close_thread_tables() after that, we no longer
can collect engine's counter variables, as they use the data
structures that are located in the Explain Data Structures.

Also, these delete_explain_query() calls are redundant, as
sp_lex_keeper::reset_lex_and_exec_core() has another
delete_explain_query() call, which is located in the right
location after the close_thread_tables() call.

mysql-test/main/sp.result

@@ -8972,3 +8972,15 @@ select @counter;
 5
 drop function f1;
 drop table t1,t2;
+# 
+# MDEV-31877: ASAN errors in Exec_time_tracker::get_cycles with innodb slow log verbosity
+# 
+CREATE TABLE t1 (a INT, b INT);
+INSERT INTO t1 VALUES (1,2);
+SET @tmp=@@log_slow_verbosity;
+SET SESSION log_slow_verbosity= 'innodb';
+BEGIN NOT ATOMIC DECLARE r ROW TYPE OF t1 DEFAULT (SELECT * FROM t1); SELECT r.a; END $
+r.a
+1
+SET SESSION log_slow_verbosity= @tmp;
+DROP TABLE t1;

mysql-test/main/sp.test

@@ -10573,3 +10573,19 @@ select f1(col1) from t2 order by col2 desc limit 5;
 select @counter;
 drop function f1;
 drop table t1,t2;
+
+--echo # 
+--echo # MDEV-31877: ASAN errors in Exec_time_tracker::get_cycles with innodb slow log verbosity
+--echo # 
+CREATE TABLE t1 (a INT, b INT);
+INSERT INTO t1 VALUES (1,2);
+SET @tmp=@@log_slow_verbosity;
+SET SESSION log_slow_verbosity= 'innodb';
+--delimiter $
+BEGIN NOT ATOMIC DECLARE r ROW TYPE OF t1 DEFAULT (SELECT * FROM t1); SELECT r.a; END $
+--delimiter ;
+
+SET SESSION log_slow_verbosity= @tmp;
+# Cleanup
+DROP TABLE t1;
+

sql/sp_head.cc

@@ -3807,7 +3807,6 @@ int
 sp_instr_set::exec_core(THD *thd, uint *nextp)
 {
   int res= get_rcontext(thd)->set_variable(thd, m_offset, &m_value);
-  delete_explain_query(thd->lex);
   *nextp = m_ip+1;
   return res;
 }
@@ -3849,7 +3848,6 @@ sp_instr_set_row_field::exec_core(THD *thd, uint *nextp)
   int res= get_rcontext(thd)->set_variable_row_field(thd, m_offset,
                                                      m_field_offset,
                                                      &m_value);
-  delete_explain_query(thd->lex);
   *nextp= m_ip + 1;
   return res;
 }
@@ -3897,7 +3895,6 @@ sp_instr_set_row_field_by_name::exec_core(THD *thd, uint *nextp)
   int res= get_rcontext(thd)->set_variable_row_field_by_name(thd, m_offset,
                                                              m_field_name,
                                                              &m_value);
-  delete_explain_query(thd->lex);
   *nextp= m_ip + 1;
   return res;
 }