Add run_type tag to dagrun.duration.failed timeout metric

[Vamsi-klu]

What / impact

When a Dag run timed out, the scheduler emitted the dagrun.duration.failed timing metric with only a dag_id tag. Every other dagrun.duration.* emission also carries run_type, so dashboards and alerts that segment by run_type silently dropped timed-out runs (or saw an inconsistent tag set). After this change the timeout path emits both dag_id and run_type, consistent with normal completion.

Why

The timeout branch in _schedule_dag_run hardcoded tags={"dag_id": dag_run.dag_id}, while the canonical emitter DagRun._emit_duration_stats_for_finished_state uses dag_run.stats_tags (which includes run_type). This replaces the hardcoded dict with dag_run.stats_tags. run_type is NOT NULL and low-cardinality, so the new tag set is a safe strict superset of the old one and the metric name is unchanged.

How it unblocks

Makes timeout-duration metrics consistent and usable in run_type-segmented observability. Supersedes #64768, which stalled on CI/static checks rather than design — this keeps the diff to a single value change and ships green static checks, including the metrics-registry sync check that blocked the prior attempt.

Tests

One new regression test in test_scheduler_job.py, verified to fail on the unfixed code, asserting the dagrun.duration.failed timing call carries tags={"dag_id": …, "run_type": …}. Full scheduler suite passes; mypy + pre-commit + manual static checks (incl. metrics-registry sync) are green.

closes: #64765

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Was generative AI tooling used to co-author this PR?

• Yes — Claude Code (Opus 4.8)

Generated-by: Claude Code (Opus 4.8) following the guidelines

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Important

🛠️ Maintainer triage note for @Vamsi-klu · by @potiuk · 2026-07-02 17:46 UTC

Helpful heads-up from the maintainers — please address before this PR can be reviewed (see the Pull Request quality criteria):

• This PR has merge conflicts with main. Please rebase onto the latest main and resolve them.

The ball is in your court — you've been assigned to this PR. Fix the above, then mark it Ready for review.

_{Automated triage — may be imperfect; a maintainer takes the next look.}

[potiuk]

Correct and nicely scoped — switching to dag_run.stats_tags makes the timeout path consistent with DagRun._emit_duration_stats_for_finished_state, and the test pins the tag set. The newsfragment is appropriate since the metric shape is user-visible.

One thing worth being aware of downstream: dashboards keyed on the old tag set will now see an extra dimension.

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Drafted-by: Claude Code (Opus 5); reviewed by @potiuk before posting