feat(temporal): add composite metric (backlog + running workflow count)

[Sanil2108]

• Add includeRunningWorkflowCount (default: true) to use backlog + running workflow count as the scaling metric, avoiding premature scale-down when workers are fast and backlog is often zero.
• Add optional workflowTaskQueueForCount to scope running count by workflow task queue (e.g. when scaling activity workers).
• getRunningWorkflowCount() uses CountWorkflow with visibility query ExecutionStatus = 'Running' AND TaskQueue = ''.
• On CountWorkflow failure, fall back to backlog-only and log at V(1).
• Add tests for new metadata and default composite behavior.

Provide a description of what has been changed

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Fixes #7459

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