bugfix: Expose new environment variables to Patroni run

[arthlr]

Summary

This Pull Request ensures that the newly introduced environment variables — KUBERNETES_LEADER_LABEL_VALUE and KUBERNETES_STANDBY_LEADER_LABEL_VALUE — are correctly passed to the Patroni process by removing them from the filtering logic in the entrypoint script.

Context & Motivation

The variables KUBERNETES_LEADER_LABEL_VALUE and KUBERNETES_STANDBY_LEADER_LABEL_VALUE were unintentionally excluded from the environment passed to the running Patroni process due to the default filtering logic in the Spilo entrypoint script. As a result, their values were not available at runtime rendering the configuration ineffective.

Specifically, when Patroni invokes the callback_role.py script, it relies on the LEADER_LABEL_VALUE constant, which is expected to derive its value from the KUBERNETES_LEADER_LABEL_VALUE environment variable. Since this variable was not passed through, the callback logic silently falls back to the default value (master), breaking expected behavior in customized deployments.

Impact

• No breaking changes expected.
• Enables correct configuration of Kubernetes leader election behavior when using these new environment variables.
• Backward compatible for users not using these variables.

This aims to fix the issue #1105