Warn when a dbt project contains tests: instead of data_tests:

[dbeatty10]

Describe the feature

Raise a warning whenever the tests: config is used instead of data_tests: (in order to disambiguate from unit_tests:).

This scenario is going to be removed as a deprecation warning in dbt-core when dbt-labs/dbt-core#10564 is resolved.

But data_tests: is the recommended best practice (even if tests: is supported indefinitely by dbt-core).

Describe alternatives you've considered

1. Keeping it as as deprecation warning in dbt-core.
2. Converting to just an info level or debug level message in the dbt-core logs.
3. Create some new dbt package that handles things like this, #477, etc.

Additional context

data_tests: was added in v1.8, so any versions of dbt-core earlier than that can't use it.

This is similar in spirit to #477.

Who will this benefit?

Users that want to be aware of best practices that aren't official warnings in dbt-core.

[dave-connors-3]

given that we are removing this warning and do not plan to remove back compatibility, we are going to close this for now!