MDEV-24172: innodb stats table last_update is TIMESTAMP

The last_updated column of innodb_table_stats and innodb_index_stats
hasn't been DATA_FIXBINARY for many years.

Innodb represents TIMESTAMP as INT of length 4. Let's test it with this
and stop hiding the result in mysql_upgrade test.

Reviewer: Marko

mysql-test/r/mysql_upgrade.result

@@ -476,8 +476,6 @@ even_longer_user_name_number_3_to_test_the_grantor_and_definer_field_length@loca
 DROP USER very_long_user_name_number_1, very_long_user_name_number_2, even_longer_user_name_number_3_to_test_the_grantor_and_definer_field_length@localhost;
 DROP PROCEDURE test.pr;
 use test;
-call mtr.add_suppression('Column last_update in table `mysql`.`innodb_table_stats` is INT NOT NULL but should be');
-alter table mysql.innodb_table_stats modify last_update int not null;
 create table extralongname_extralongname_extralongname_extralongname_ext (
 id int(10) unsigned not null,
 created_date date not null,

mysql-test/t/mysql_upgrade.test

@@ -173,8 +173,6 @@ DROP PROCEDURE test.pr;
 # MDEV-13274 mysql_upgrade fails if dbname+tablename+partioname > 64 chars
 #
 use test;
-call mtr.add_suppression('Column last_update in table `mysql`.`innodb_table_stats` is INT NOT NULL but should be');
-alter table mysql.innodb_table_stats modify last_update int not null;
 
 create table extralongname_extralongname_extralongname_extralongname_ext (
   id int(10) unsigned not null,

storage/innobase/dict/dict0stats.cc

@@ -178,8 +178,8 @@ dict_stats_persistent_storage_check(
 		{"table_name", DATA_VARMYSQL,
 			DATA_NOT_NULL, 597},
 
-		{"last_update", DATA_FIXBINARY,
-			DATA_NOT_NULL, 4},
+		{"last_update", DATA_INT,
+			DATA_NOT_NULL | DATA_UNSIGNED, 4},
 
 		{"n_rows", DATA_INT,
 			DATA_NOT_NULL | DATA_UNSIGNED, 8},
@@ -209,8 +209,8 @@ dict_stats_persistent_storage_check(
 		{"index_name", DATA_VARMYSQL,
 			DATA_NOT_NULL, 192},
 
-		{"last_update", DATA_FIXBINARY,
-			DATA_NOT_NULL, 4},
+		{"last_update", DATA_INT,
+			DATA_NOT_NULL | DATA_UNSIGNED, 4},
 
 		{"stat_name", DATA_VARMYSQL,
 			DATA_NOT_NULL, 64*3},