Incorrect response serializer in OpenAPI for CreateTrainingProcess

The API docs for the CreateTrainingProcess endpoint show that its response includes the same attributes as the request, where it actually only returns a DataImport ID. The DataImport UUID is returned by overriding the create method on the API view and bypassing the serializers entirely, which is discouraged.

The serializer should be changed so that it includes a read-only ID attribute for the DataImport's ID, and all of its other attributes are write-only. This will remove the create override.