Minor main.yml Improvements

[emmyoop]

Housekeeping

• [X] I am a maintainer of dbt-core

Short description

Make main.yml more efficient by pulling out the code quality tests and adjusting the scheduled testing.

Acceptance criteria

• Pull out the code quality checks to a separate workflow that always runs
• New code quality check should be a required check
• Remaining jobs in main.yml (unit/functional/builds) should only run when necesary
  • exclude when the only files changes are in .github or .changes. Possibly others?
• Update the scheduled branch testing to also run the code quality checks now that they're in a separate workflow
  • There are 2 options to do this
    • backport the workflow split all the way back to 1.0
    • add logic to run different workflow files based on the branch that's running. This would require changes to teh workflow in actions so may not be worth the lift.

Suggested Tests

This is just tesating

Impact to Other Teams

None

Will backports be required?

Possibly. But no releases would be related to the backports. Depends on how we handle scheduled testing.

Context

Determine if the main.yml workflow is run anywhere else that we would also need to run the code quality checks.

For example, we run the main.yml workflow in dbt-common but since it's just testing functionality with dbt-common, it's okay to skip code-quality checks there so it requires no updates.