MDEV-21360 global debug_dbug pre-test value restoration issues

mysql-test/suite/innodb/r/redo_log_during_checkpoint.result

@@ -4,8 +4,8 @@ SET GLOBAL innodb_master_thread_disabled_debug = 1;
 SET GLOBAL innodb_log_checkpoint_now = 1;
 CREATE DATABASE very_long_database_name;
 USE very_long_database_name;
-set debug_dbug = '+d,increase_mtr_checkpoint_size';
-set debug_dbug = '+d,crash_after_checkpoint';
+SET debug_dbug = '+d,increase_mtr_checkpoint_size';
+SET debug_dbug = '+d,crash_after_checkpoint';
 set global innodb_log_checkpoint_now = 1;
 ERROR HY000: Lost connection to MySQL server during query
 # Skip MLOG_FILE_NAME redo records during recovery
@@ -18,7 +18,7 @@ SET GLOBAL innodb_log_checkpoint_now = 1;
 # exceeds LOG_CHECKPOINT_FREE_PER_THREAD size during checkpoint.
 CREATE DATABASE very_long_database_name;
 USE very_long_database_name;
-set debug_dbug = '+d,crash_after_checkpoint';
+SET debug_dbug = '+d,crash_after_checkpoint';
 set global innodb_log_checkpoint_now = 1;
 ERROR HY000: Lost connection to MySQL server during query
 # Skip MLOG_FILE_NAME redo records during recovery

mysql-test/suite/innodb_gis/r/rtree_debug.result

@@ -42,7 +42,7 @@ SET @save_dbug = @@SESSION.debug_dbug;
 SET debug_dbug='+d,row_merge_ins_spatial_fail';
 create spatial index idx2 on t1(c2);
 ERROR HY000: Got error 1000 "Unknown error 1000" from storage engine InnoDB
-SET debug_dbug = @save_dbug;
+SET @@SESSION.debug_dbug = @save_dbug;
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (