Why is validation_definition_store_name not part of the great_expectations.yaml spec?

[CrossNox]

I'm trying to set up GX in such a way that I can use a single yaml to run both production and development environments.

On config_variables I have env for this purpose. Then, e.g. expectations_store_name could be ${env}_expectations_store, with dev_expectations_store and prd_expectations_store configured as Filesystem/S3 backends, respectively. The S3 backend could be populated on CI.

But now, what should I do with the validation_definition_store ?