Refactor manual (i.e., non-update-pipeline) dbt _standardized and _clean stage model-running tasks into an importable task_group

[MattTriano]

Specifically I'm talking about the tasks used in the DAG in this file.

At present, I've just been manually changing which table is imported and then running the DAG, and that will still be part of the dev process, but documenting this workflow will be much easier and cleaner after ~200 lines of task functions are encapsulated into a task_group.