fix: health check port handling

[prassanna-ravishankar]

env vars dont get populated by the manifest and the value is only available using EnvironmentVariables.refresh().

Current code errors on missing value in manifest

[Copilot]

Pull Request Overview

This PR fixes health check port handling in the Temporal worker by addressing an issue where environment variables are not populated from the manifest, causing errors when trying to access the HEALTH_CHECK_PORT environment variable directly.

• Changes the parameter type from int to int | None to allow optional health check port
• Implements fallback logic using EnvironmentVariables.refresh() when port is not provided

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