ADAP-1124: Establish shared workflows for the monorepo migration

[mikealfare]

Problem

We're moving to a monorepo for adapters. This will require workflows that can be reused across adapters.

Solution

Migrate workflows from dbt-athena, which is already technically a monorepo (two packages) and make updates as needed to generalize. Update the workflows to support dbt-adapters and dbt-tests-adapter in the short term until their folder structures are updated, and then remove any existing workflows which are no longer necessary. Use this refactor as an opportunity to also clean up existing workflows which will live on in the monorepo.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development, and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc.) or this PR has already received feedback and approval from Product or DX

[github-actions]

Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the contributing guide.

[mikealfare]

Successful atomic workflow runs:

• _code-quality: https://github.com/dbt-labs/dbt-adapters/actions/runs/12214961654
• _generate-changelog (exists): https://github.com/dbt-labs/dbt-adapters/actions/runs/12215073859
• _generate-changelog (does not exist): https://github.com/dbt-labs/dbt-adapters/actions/runs/12215088370
  • https://github.com/dbt-labs/dbt-adapters/blob/prep-release/dbt-adapters/12215088370/.changes/1.10.5.md
• _publish-pypi: https://github.com/dbt-labs/dbt-adapters/actions/runs/12215319147
  • https://test.pypi.org/project/dbt-adapters/1.10.4/
  • the verification step failed, I think due to a bad internet connection
• _unit-tests: https://github.com/dbt-labs/dbt-adapters/actions/runs/12214989155
• _verify-build: https://github.com/dbt-labs/dbt-adapters/actions/runs/12215032466

I can't validate _changelog-entry-check because the action we use inspects the trigger method to run.
I can't validate _publish-internal because we don't publish dbt-adapters internally yet.
I added pull_request as a trigger and confirmed that changelog entry check, unit tests, code quality, and build verification checks ran as expected.