Ref T4379. Long ago, the "Project" vs "ProjectProfile" split was intended to allow a bunch of special fields on projects without burdening the simple use cases, but CustomField handles that far better and far more generally, and doing this makes using ApplicationTransactions a pain to get right, so get rid of it.
The only remaining field is profileImagePHID, which we can just move to the main Project object. This is custom enough that I think it's reasonable not to express it as a custom field.