Prep for 1.8.4 release

[benc-db]

Description

Prepare for 1.8.4 release. Also updating the integration test runner so that it doesn't kick off integration tests on these release PRs going forward.

Checklist

• [x] I have run this code in development and it appears to resolve the stated issue
• [x] This PR includes tests, or tests are not required/relevant for this PR
• [x] I have updated the CHANGELOG.md and added information about my change to the "dbt-databricks next" section.