[migration] Improve update of in-memory schema during 3.18 CWAttribute.defaultval change We weren't updating the schema properly so a bunch of structures still had the old rdef with 'String' as object. That caused failures to add new attributes later in the migration as their default value would be a Binary object but the schema would expect a String. Closes #3683640

for table, column in [
        ('transactions', 'tx_time'),
        ('tx_entity_actions', 'tx_uuid'),
        ('tx_relation_actions', 'tx_uuid')]:
    session.cnxset.source('system').create_index(session, table, column)

commit()