Support Environment Variable Substitution for clusterMetadata in Temporal Configuration Templates

[mhmtszr]

Currently, Temporal’s template configuration does not support substituting environment variables in the clusterMetadata section. This limitation makes it difficult to dynamically configure multi-cluster setups or enable/disable features like enableGlobalNamespace without manually modifying the configuration file.

Expected Behavior:

• Support for environment variables within the clusterMetadata section.
• Ability to set dynamic cluster configurations (e.g., enable global namespaces, multi-cluster addresses) through environment variables.

Example:

clusterMetadata:
  enableGlobalNamespace: {{ env "TEMPORAL_CLUSTER_METADATA_ENABLE_GLOBAL_NAMESPACE" | default "false" }}