Remove fallback mechanism for old work_item_types.id

For instances that went thorough the cleanup process of work_item_types.id values (change to sequential values 1 - 9) [Cells 1.0] Default Work Item Types: Ensure wor... (&15272 - closed)

We need to remove the fallback mechanism of old IDs in a major release preferably. Not mandatory as the API is marked as an experiment