Prefix secrets with DBT_ENV_SECRET_ for test env vars

[mikealfare]

resolves dbt-labs/adapters-team-private#135

Problem

Environment variables containing secrets need to be prefixed with DBT_ENV_SECRET_ to be handled properly in dbt-core.

Solution

• prefix testing environment variables with DBT_ENV_SECRET_
• update the places where they get read in in /tests
• update workflows that inject secrets

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 dbt-spark contributing guide.

[mikealfare]

Running the integration tests against this branch manually: https://github.com/dbt-labs/dbt-spark/actions/runs/8840556857

[mikealfare]

New CI run: https://github.com/dbt-labs/dbt-spark/actions/runs/8853477253

[mikealfare]

New CI run: https://github.com/dbt-labs/dbt-spark/actions/runs/8854178871

[mikealfare]

It looks like the host isn't being pulled in for the databricks test profiles.