refs #16661 [master-v5] remove unique constraint from migration script v5

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

@@ -194,14 +194,6 @@ ALTER TABLE session
   MODIFY COLUMN data mediumtext,
   MODIFY COLUMN created datetime NOT NULL DEFAULT '2000-01-01 00:00:00';
   
--- Apply constraint modifications  
-
-ALTER TABLE session
-   DROP INDEX last_used;
-   
-ALTER TABLE session
-  ADD UNIQUE(last_used); 
-  
 -- Set chracter set to utf8  
 
 ALTER TABLE session