chore: Explicitly disable multi-statements in Snowflake

[tomasfarias]

Problem

Multi-statements are disabled in Snowflake, but this is implicit.

Changes

Make it explicit by setting the approppiate session parameter.

How did you test this code?

Ran Snowflake tests. All passing.

👉 Stay up-to-date with PostHog coding conventions for a smoother review.

Publish to changelog?

No

Docs update

No

🤖 Agent context

Used it to write it, then formatted the comment.

[greptile-apps]

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
products/batch_exports/backend/temporal/destinations/snowflake_batch_export.py:588-592
The session-parameters dict is defined inline here and as `_SNOWFLAKE_SESSION_PARAMETERS` in the destination-tests file — two places to update if the parameter set ever changes. Extracting a module-level constant here would follow the same pattern used in the test file and satisfy OnceAndOnlyOnce within this module.

```suggestion
                    # Pin Snowflake's per-session statement count to 1 to block
                    # multi-statement execution. This is already the connector default,
                    # but setting it explicitly means an account-level override cannot
                    # accidentally enable multi-statement execution.
                    session_parameters=_SNOWFLAKE_SESSION_PARAMETERS,
```

_{Reviews (1): Last reviewed commit: "chore: Explicitly disable multi-statemen..." | Re-trigger Greptile}

[github-actions]

Simple defensive hardening that explicitly sets MULTI_STATEMENT_COUNT=1 to prevent account-level overrides from enabling multi-statement execution. The bot comment about extracting a shared constant is a style suggestion, not a showstopper.

[deployment-status-posthog]

Deploy status

Environment	Status	Deployed At	Workflow
dev	✅ Deployed	2026-05-27 08:43 UTC	Run
prod-us	✅ Deployed	2026-05-27 09:07 UTC	Run
prod-eu	✅ Deployed	2026-05-27 09:11 UTC	Run