make sure tables are UTF8 capable

As discussed at #7742 (comment) make sure that tables have correct char set.

doc/update/7.3-to-7.4.md

@@ -26,6 +26,15 @@ SELECT CONCAT('ALTER TABLE gitlabhq_production.', table_name, ' ENGINE=InnoDB;')
 
 # If previous query returned results, copy & run all outputed SQL statements
 
+# Convert all tables to correct character set
+SET foreign_key_checks = 0;
+SELECT CONCAT('ALTER TABLE gitlabhq_production.', table_name, ' CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;') AS 'Copy & run these SQL statements:' FROM information_schema.tables WHERE table_schema = 'gitlabhq_production' AND `TABLE_COLLATION` <> 'utf8_unicode_ci' AND `TABLE_TYPE` = 'BASE TABLE';
+
+# If previous query returned results, copy & run all outputed SQL statements
+
+# turn foreign key checks back on
+SET foreign_key_checks = 1;
+
 # Find MySQL users
 mysql> SELECT user FROM mysql.user WHERE user LIKE '%git%';