Fix Triggerer subprocess sys.path gap for DAG bundle helpers

[gaurav0107]

TriggerRunner.create_triggers() now initializes the active DAG bundle and appends its root to sys.path before importing trigger classes, matching the pattern established for the task runner, callback supervisor, DAG processor, and CLI in #55894. Triggers whose classpath points into dags/ (e.g. helpers.emr_sensor_helpers.MyTrigger) no longer raise ModuleNotFoundError at deserialization.

Changes

1. airflow-core/src/airflow/executors/workloads/trigger.py — add optional bundle_info: BundleInfo | None = None field to the RunTrigger workload. Optional because asset-based triggers have no associated bundle.
2. airflow-core/src/airflow/jobs/triggerer_job_runner.py:
   • TriggerRunner._create_workload: resolve BundleInfo(name=..., version=...) from serialized_dag_model.dag_version and plumb it into both non-asset RunTrigger(...) construction sites. Asset-based branch keeps bundle_info=None — asset triggers ship as provider-installed classes, not bundle-local helpers.
   • New TriggerRunner._ensure_bundle_on_syspath helper mirroring callback_supervisor.py: if a bundle is specified, initialize it via DagBundlesManager().get_bundle(...) and append str(bundle.path) to sys.path (deduped via self._bundle_paths_added). Failures log warning with exc_info but do not crash the triggerer — same defensiveness as the callback supervisor.
   • TriggerRunner.create_triggers: call _ensure_bundle_on_syspath(workload.bundle_info) immediately before get_trigger_by_classpath(workload.classpath).
3. airflow-core/tests/unit/jobs/test_triggerer_job.py — three new unit tests covering the dedup path (appends once), the no-op paths (None, empty name, DagBundlesManager never instantiated), and the exception path (swallowed, sys.path unchanged). Each test restores sys.path in a try/finally to avoid cross-test contamination.

closes: #65455

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• Yes — Claude Opus 4.7 (1M context)

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