Correct columns covered in migrations_instance_uuid_and_status_idx

Migration 142 added a new index migrations_instance_uuid_and_status_idx
that covers columns deleted, instance_uuid and status, but the index
added to the model only covers instance_uuid and status.

Change-Id: I6ffdeabbab54223b2be844048917588adaceb9bb
Partially-implements: blueprint validate-migrations-and-model
Merge "Correct columns covered in migrations_instance_uuid_and_status_idx"