Restore accidentally removed variable assignment in the scheduler_job_runner

[xBis7]

While running some manual tests with the metrics enabled, I noticed that the scheduler started exiting after triggering a few dags.

This is the stacktrace that I'm seeing in the logs

2026-02-10T10:21:07.655259Z [error    ] Exception when executing SchedulerJob._run_scheduler_loop
p [airflow.jobs.scheduler_job_runner.SchedulerJobRunner] loc=scheduler_job_runner.py:1324
Traceback (most recent call last):
  File "/opt/airflow/airflow-core/src/airflow/jobs/scheduler_job_runner.py", line 1319, in _execute
    self._run_scheduler_loop()
  File "/opt/airflow/airflow-core/src/airflow/jobs/scheduler_job_runner.py", line 1666, in _run_scheduler_loop
    next_event = timers.run(blocking=False)
  File "/usr/python/lib/python3.10/sched.py", line 151, in run
    action(*argument, **kwargs)
  File "/opt/airflow/airflow-core/src/airflow/utils/event_scheduler.py", line 40, in repeat
    action(*args, **kwargs)
  File "/opt/airflow/airflow-core/src/airflow/utils/session.py", line 100, in wrapper
    return func(*args, session=session, **kwargs)  # type: ignore[arg-type]
  File "/opt/airflow/airflow-core/src/airflow/jobs/scheduler_job_runner.py", line 2647, in _emit_ti_metrics
    extra_tags={"queue": queue, "dag_id": dag_id, "task_id": task_id},
UnboundLocalError: local variable 'queue' referenced before assignment
2026-02-10T10:21:07.699406Z [info     ] Shutting down LocalExecutor; waiting for running tasks t

This is actually my fault because in a previous PR of mine, #53722, I accidentally removed the variable assignment

This is the exact diff from the PR

-  dag_id, task_id, queue = prev_key
-  Stats.gauge(f"ti.{state}.{queue}.{dag_id}.{task_id}", 0)
-  Stats.gauge(f"ti.{state}", 0, tags={"queue": queue, "dag_id": dag_id, "task_id": task_id})
+  DualStatsManager.gauge(
+          f"ti.{state}",
+          0,
+          tags={},
+          extra_tags={"queue": queue, "dag_id": dag_id, "task_id": task_id},
+  )

This is the line that shouldn't have been removed

dag_id, task_id, queue = prev_key

I tested it manually and the error is gone.

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[xBis7]

@shahar1 @potiuk Thank you!