feat: make TOWER_ENVIRONMENT ordinary passthrough in local runs

[socksy]

make_env_vars injected TOWER_ENVIRONMENT as the last step of building a run's env, unconditionally. Because it ran last it overwrote any value a caller had already put in the env map — the hardcoded value always won.

This drops the special case so the var passes through like everything else. make_env_vars no longer injects it, and loses its now-unused env param along with the dead threading through execute_bash_program. The local run path in run.rs supplies it explicitly from the resolved --environment arg instead, next to the existing TOWER__RUNTIME__IS_LOCAL. The arg defaults to default, so a local run with no flag still gets TOWER_ENVIRONMENT=default like before.

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 9d5590f5-d637-4860-b5b2-49236d6d010c

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feature/passthrough-tower-environment

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}