[LDEV-1229] Add unique index on transitionsFor the 2.0.3 updater, existing duplicate rows need to be deleted from the lams_learning_transition table, this SQL code has been added to the alter_203_transition.sql
LDEV-1229: Add a unique key on the activity columns in transition. Somehow we are ending up with duplicate rows in the database, which stops the design being opened. This will stop the bad data being written to the database.