[v3-3-test] Add partition clear support to REST API matching the CLI (#68702)

[github-actions]

• API: Add partition clear support to REST API to match the CLI

clearDagRuns now accepts partition_key / partition_date window selectors
as an alternative to an explicit run list. Add POST /dags/{dag_id}/clearPartitions
to reset partition_key/partition_date on matching runs, with optional
task-instance clear — REST parity with airflow dags clear / airflow partitions clear.

• API: Deduplicate partition selector fields across clear request bodies

Extract the shared partition_key / partition_date window fields and their date-order check into a PartitionSelectorMixin reused by BulkDAGRunClearBody and ClearPartitionsBody, and replace the repeated partition-selector presence checks with a has_partition_selectors property. No behavior change.

• Scope partition-clear task instance queries to the target dag

Add a dag_id filter to the task-instance lookups in both the REST clear_partition_fields service and the airflow partitions clear CLI so a run_id shared across dags no longer clears another dag's task instances, and collapse the per-run dry-run task-instance lookups into a single batched count query.

• Share the partition date-window filter across clear paths

Extract the resolve_day_bound partition_date window resolution duplicated across the REST clear_dag_runs route, the clear_partition_fields service, and the airflow partitions clear CLI into a single DagRun.apply_partition_date_window helper so the three cannot drift.

• Share the partition-clear core between the REST API and the CLI

Extract the partition column-reset, task-instance batching, and dry-run counting into a single DagRun.clear_partition_runs helper reused by the clearPartitions REST endpoint and the airflow partitions clear CLI, replacing the two parallel implementations. The CLI keeps its per-run output through an optional callback. No behavior change.

• Fix partition clear commands widening sub-day windows to the whole day

dags clear and partitions clear passed user-supplied datetimes
through resolve_day_bound(.date()), which stripped the time component
and expanded any sub-day bound to local midnight. On an hourly
partitioned Dag, --partition-date-start 08:00 --partition-date-end 08:00 cleared all 24 partitions instead of just the 08:00 one.

Adds localize_partition_datetime to the Timetable protocol (base:
UTC pass-through; CronMixin: wall-clock re-interpreted in the
timetable's local timezone, same logic as #68718). Removes the
now-redundant private _localize_wall_clock_to_timetable_timezone from
CronPartitionTimetable. Updates apply_partition_date_window to use
the new method with an inclusive <= end bound instead of the old
half-open < next_midnight form.

• Update REST datamodel descriptions to reflect sub-day precision

• Share partition selection-mode validation across clear request bodies

BulkDAGRunClearBody and ClearPartitionsBody duplicated the same
"exactly one selection mode" rule, including the partition-window
definition and the selector-enumeration error message, which would
drift independently. Move the shared check onto PartitionSelectorMixin
so the partition-selector semantics live in one place.

• Drop sub-day-precision wording from partition clear CLI help

The "sub-day precision is preserved" phrasing framed the help against a
since-fixed truncation bug, which is meaningless to a reader seeing the
text fresh. The timezone re-interpretation note plus the date-only ->
midnight rule already convey that the time of day is honoured.

• Remove unused resolve_day_bound

• Refactor tests

• regen docs

• Fix test failure

• Fix ruff F402 and docs spelling failing CI on partition-clear branch

A loop variable shadowed the imported task decorator (ruff F402) and a
British-spelled word in a new docstring tripped the en_US docs spell-check.

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(cherry picked from commit a0805a8)

Co-authored-by: Wei Lee weilee.rx@gmail.com
Co-authored-by: Rahul Vats rah.sharma11@gmail.com