Fix circular import in DB migration job

[LipuFei]

Related to #30988 and #31033

Version: 2.6.1rc1
Docker image: apache/airflow:2.6.1rc1-python3.10

The root-level import of TaskInstance will cause a circular import problem when both Kubernetes and Sentry are enabled. This will show up in the DB migration job when I use the official Helm chart 1.9.0 to deploy.

I have tested this fix by patching the image apache/airflow:2.6.1rc1-python3.10 with this kubernetes_executor.py

Here is the stack trace:

Traceback (most recent call last):
File "/home/airflow/.local/bin/airflow", line 8, in <module>
sys.exit(main())
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/__main__.py", line 48, in main
args.func(args)
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/cli/cli_config.py", line 51, in command
return func(*args, **kwargs)
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/utils/cli.py", line 112, in wrapper
return f(*args, **kwargs)
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/cli/commands/db_command.py", line 84, in upgradedb
db.upgradedb(
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/utils/session.py", line 76, in wrapper
return func(*args, session=session, **kwargs)
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/utils/db.py", line 1545, in upgradedb
import_all_models()
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/models/__init__.py", line 60, in import_all_models
__getattr__(name)
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/models/__init__.py", line 78, in __getattr__
val = import_string(f"{path}.{name}")
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/utils/module_loading.py", line 36, in import_string
module = import_module(module_path)
File "/usr/local/lib/python3.10/importlib/__init__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
File "<frozen importlib._bootstrap>", line 1006, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 688, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 883, in exec_module
File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/models/dag.py", line 82, in <module>
from airflow.models.dagrun import DagRun
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/models/dagrun.py", line 57, in <module>
from airflow.models.taskinstance import TaskInstance as TI
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/models/taskinstance.py", line 100, in <module>
from airflow.sentry import Sentry
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/sentry.py", line 195, in <module>
Sentry = ConfiguredSentry()
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/sentry.py", line 92, in __init__
executor_class, _ = ExecutorLoader.import_default_executor_cls()
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/executors/executor_loader.py", line 158, in import_default_executor_cls
executor, source = cls.import_executor_cls(executor_name)
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/executors/executor_loader.py", line 134, in import_executor_cls
return _import_and_validate(cls.executors[executor_name]), ConnectorSource.CORE
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/executors/executor_loader.py", line 129, in _import_and_validate
executor = import_string(path)
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/utils/module_loading.py", line 36, in import_string
module = import_module(module_path)
File "/usr/local/lib/python3.10/importlib/__init__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/executors/celery_kubernetes_executor.py", line 26, in <module>
from airflow.executors.kubernetes_executor import KubernetesExecutor
File "/home/airflow/.local/lib/python3.10/site-packages/airflow/executors/kubernetes_executor.py", line 49, in <module>
from airflow.models.taskinstance import TaskInstance
ImportError: cannot import name 'TaskInstance' from partially initialized module 'airflow.models.taskinstance' (most likely due to a circular import) (/home/airflow/.local/lib/python3.10/site-packages/airflow/models/taskinstance.py)