Fix import errors updating DAGs in other bundles

[gopidesupavan]

Import error updates in dag processing were matching DagModel rows by relative_fileloc only. When two DAG bundles contained files with the same relative path, an import error in one bundle could incorrectly mark the other bundle’s DAG as having import errors and even overwrite its bundle_name.

This is easily reproducible:

1. Configure two DAG bundles that contain the same relative file name, for example:

files/bundle_a/example_dag.py
files/bundle_b/example_dag.py

2. Set the bundle config:
   export AIRFLOW__DAG_PROCESSOR__DAG_BUNDLE_CONFIG_LIST='[
   {"name":"bundle_a","classpath":"airflow.dag_processing.bundles.local.LocalDagBundle","kwargs":{"path":"/files/bundle_a","refresh_interval":0}},
   {"name":"bundle_b","classpath":"airflow.dag_processing.bundles.local.LocalDagBundle","kwargs":{"path":"/files/bundle_b","refresh_interval":0}}
   ]'

3. Parse both bundles successfully:

4. Introduce an import error only in files/bundle_a/example_dag.py.

5. Reparse only bundle_a

airflow dags reserialize --bundle-name bundle_a

select dag_id, bundle_name, relative_fileloc, has_import_errors
from dag
where relative_fileloc = 'example_dag.py'
order by bundle_name, dag_id;

Before this fix, you can end up with both records marked as having import errors, even though only the DAG in bundle_a is broken.

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[github-actions]

Backport successfully created: v3-1-test

Note: As of Merging PRs targeted for Airflow 3.X
the committer who merges the PR is responsible for backporting the PRs that are bug fixes (generally speaking) to the maintenance branches.

In matter of doubt please ask in #release-management Slack channel.

Status	Branch	Result
✅	v3-1-test