Disable national measure check task

I can't find the exact story, but it was decided to report on invalid national Measures instead of deleting them. That is why we sometimes receive Tariff update emails with conformance errors and can investigate what is happening.

I don't think this task did anything destructive to production (or any other environment) since we moved to point database structure and all Model-level validations were rewritten to use our own conformance validator. So `measure.valid?` was always true.