refs #16234 [master-v5] do not drop (non-existing) column username_id and...

refs #16234 [master-v5] do not drop (non-existing) column username_id and user_id_key unique constraint

module/finc/sql/migrations/mysql/migrateData_Vufind1ToVufind5_Common.sql

@@ -52,16 +52,6 @@ ALTER TABLE user
   ADD COLUMN last_login timestamp NOT NULL DEFAULT '2000-01-01 00:00:00',
   ADD COLUMN auth_method varchar(50) DEFAULT NULL;
 
--- Drop columns
-
-ALTER TABLE user
-  DROP COLUMN username_id;           
-  
--- Apply constraint modifications  
-
-ALTER TABLE user
-  DROP INDEX user_id_key;
-
 ALTER TABLE user
   ADD UNIQUE(username),
   ADD UNIQUE(cat_id);