Update integration test workflow to swap `dbt-adapters` branches instead of `dbt-core`

[mikealfare]

Housekeeping

• [x] I am a maintainer of dbt-adapters

Short description

We need to update the script that swaps branches for functional testing against dbt-core to reference dbt-adapters as well as the workflow that references this script.

Context

We used to point to different branches of core for cross-repo testing. However, we should now be pointing to different branches of dbt-adapters since that is the new dependency.

We may want to offer separate options for dbt-adapters and dbt-tests-adapter even though they're in the same repo. Often times we only need to update tests or only functional code. It would be useful to test one against the other to ensure we're changing only what we expect.

We may also want to offer a separate option for other dbt-managed repos, e.g. dbt-common, dbt-artifacts, etc. This may also get used by maintainers of those repos to regression test against downstream impacts.

Acceptance criteria

- [ ] I can run the integration test workflow against a specific branch of `dbt-adapters`
- [ ] I can run the integration test workflow against a specific branch of `dbt-tests-adapter`
- [ ] I can run the integration test workflow against a specific branch of `dbt-common`
- [ ] I don't need to create a PR to invoke this process (though it would obviously still be possible by editing the `pyproject.toml`/`dev-requiremnts.txt` file)

Suggested tests

 - [ ] Execute the workflow off of this branch and test against branches other than `main` on other repos; link the run as a comment

Consequences

• This is useful to maintainers of dbt-adapters, dbt-tests-adapter, dbt-common, dbt-core, dbt-mantle, and all of the first party adapter implementations. It will allow for easier cross repo testing.
• This will reduce PR noise since PRs will no longer be necessary to test against branches other than main. This is how it used to be prior to the dbt-adapters/dbt-core split.

[github-actions[bot]]

This issue has been marked as Stale because it has been open for 180 days with no activity. If you would like the issue to remain open, please comment on the issue or else it will be closed in 7 days.

[github-actions[bot]]

Although we are closing this issue as stale, it's not gone forever. Issues can be reopened if there is renewed community interest. Just add a comment to notify the maintainers.