Avoid row locks for queued executor events

[dsherniiazov]

closes: #66794

Queued executor events only need to persist external_executor_id, so they should not go through the scheduler path that locks task instance rows with FOR UPDATE SKIP LOCKED.

This change processes QUEUED executor events with a direct UPDATE, while keeping RUNNING, SUCCESS, FAILED, and RESTARTING events on the existing locked path.

Added regression coverage for:

• queued-only executor events updating external_executor_id without row locks
• mixed queued and failed executor events where only the failed event uses the locked path

Tests:

• uv run --package apache-airflow-core ruff check airflow-core/src/airflow/jobs/scheduler_job_runner.py airflow-core/tests/unit/jobs/test_scheduler_job.py
• uv run --package apache-airflow-core ruff format --check airflow-core/src/airflow/jobs/scheduler_job_runner.py airflow-core/tests/unit/jobs/test_scheduler_job.py
• uv run --package apache-airflow-core pytest airflow-core/tests/unit/jobs/test_scheduler_job.py -q -k "process_executor_events_queued_updates_without_row_lock or process_executor_events_mixed_queued_and_failed_locks_only_failed or test_process_executor_events or test_process_executor_events_with_no_callback or test_process_executor_events_ti_requeued or test_process_executor_events_multiple_try_numbers_warns"

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