Expose Stats in sdk API and handle core backcompat

[amoghrajesh]

---

Was generative AI tooling used to co-author this PR?

• No

Stats somehow lost compat with few of the older import patterns. For example, I am adding this back:

• airflow.stats: deprecated re-export for earliest path
• airflow.observability.stats: canonical path for core (re export from _shared)
• airflow.sdk.observability: export Stats for task-sdk users like providers (re export from _shared)

Current state:

>>> from airflow.stats import Stats
<python-input-0>:1 DeprecatedImportWarning: Importing from 'airflow.stats' is deprecated. Please use 'airflow.observability.stats' instead.
>>> 
>>> 
>>> from airflow.observability.stats import Stats
>>> 
>>> 
>>> from airflow.sdk.observability.stats import Stats

---

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[amoghrajesh]

cc @xBis7 @potiuk

[xBis7]

It must have been messed up while moving the stats under shared. Initially, both airflow-core and task-sdk had their version of stats, just like with trace

https://github.com/apache/airflow/blob/main/airflow-core/src/airflow/observability/trace.py

https://github.com/apache/airflow/blob/main/task-sdk/src/airflow/sdk/observability/trace.py

[ashb]

@xBis7 Yeah, it looked like a bad rebase

[xBis7]

LGTM!

[xBis7]

While looking at #61812, a question came to mind. Should we change airflow.stats here as well?

https://github.com/astronomer/airflow/blob/98917ac30a0b2781c08cc01ba9442c02c6e4c8ba/providers/common/compat/src/airflow/providers/common/compat/sdk.py#L275

[amoghrajesh]

@xBis7 I tried to handle the lineage better in that PR

[vatsrahul1001]

Looks good! We can merge after CI is green

[amoghrajesh]

Just pushed a fix for CI, it should work now

[amoghrajesh]

No need to backport in 3.1 branch cos shared observability doesn't exist there: https://github.com/apache/airflow/blob/v3-1-test/airflow-core/src/airflow/stats.py