chore: type check test container tests

[escape0707]

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Summary

Part of #32454.

Adds a strict Pyrefly config for api/tests/test_containers_integration_tests with a exclude list for currently failing files. The wrapper now runs a second no-target Pyrefly pass for that suite, so clean files stay checked while existing bad files remain isolated.

The suite-specific config enables unannotated-return = true in addition to the strict preset.

Screenshots

N/A

Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran make lint && make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods

Verification run locally:

• ./dev/pyrefly-check-local
• blacklist regeneration check from api/tests/test_containers_integration_tests/pyrefly.toml comment