Clarify difference between `astro run <dag>` and OSS command

[paolaperaza]

Context

• There an OSS dag test command — https://airflow.apache.org/docs/apache-airflow/stable/core-concepts/executor/debug.html
• This is a little different than our in-house astro run dag_id
• We should mention the OSS thing in our Astro docs and how these are different

Two places here:

• https://docs.astronomer.io/astro/cli/astro-run
• https://docs.astronomer.io/astro/test-and-troubleshoot-locally#run-a-dag-with-astro-run

cc: @sunkickr + @jlaneve + @kentdanas

Ask

• Review this in Learn: https://docs.astronomer.io/learn/testing-airflow#debug-interactively-with-dagtestl touched docs
• To our CLI + Astro doc, have brief note on this and link to Learn if we feel like the explanation there is sufficient