[bug] do NOT allow users to define incomplete freshness config at different places and try to resolve them

[graciegoheen]

Housekeeping

• I am a maintainer of dbt-core

Short description

Currently, we allow people to define incomplete freshness config at different places and try to resolve them.

Example:

# dbt_project.yml
models:
  jaffle_shop:
    +freshness:
      build_after:
        period: hour

# orders.yml
models:
  - name: orders
    freshness:
      build_after:
        count: 1

Acceptance criteria

• Each freshness AS A CONFIG setting will need to be "complete" — can be validated independently, with both count and period set
• no merge behavior
• Either freshness is null or you must set BOTH count and period
• this should apply for all types - freshness.warn_after, freshness.error_after, freshness.build_after

[FishtownBuildBot]

Opened a new issue in dbt-labs/docs.getdbt.com: dbt-labs/docs.getdbt.com#7456