Google Vertex AI Feature Store system Dag exceeds import timeout

### Under which category would you file this issue? Providers ### Apache Airflow version `main` (development) ### What happened and how to reproduce it? The Google provider's Vertex AI Feature Store system Dag imports `google.cloud.aiplatform_v1beta1` at module scope. Importing that package triggers an expensive third-party import chain while Airflow scans the Dag file. In a clean Breeze process, importing the unmodified system Dag took 30.505 seconds and loaded `google.cloud.aiplatform_v1beta1`. This exceeds Airflow's default `dagbag_import_timeout` of 30 seconds and can surface as a Dag import timeout or a third-party circular-import failure. Steps to reproduce: 1. Check out `main` with the Google provider development dependencies installed. 2. Run the Vertex AI Feature Store system Dag import test in Breeze: ```bash BACKEND=sqlite breeze run pytest airflow-core/tests/unit/always/test_example_dags.py \ -k 'test_should_be_importable and vertex_ai_feature_store' -xvs ``` 3. Observe that parsing the Dag loads `google.cloud.aiplatform_v1beta1` at module scope and may exceed the 30-second Dag import timeout. ### What you think should happen instead? Scanning the system Dag should not load the Vertex AI Feature Store client package. Heavy Google clients and protobuf-related imports should be deferred until task execution so the Dag remains importable within the default timeout. ### Operating System macOS host with the Apache Airflow Breeze CI container, Python 3.10. ### Deployment Other Docker-based deployment ### Apache Airflow Provider(s) _No response_ ### Versions of Apache Airflow Providers _No response_ ### Official Helm Chart version Not Applicable ### Kubernetes Version _No response_ ### Helm Chart configuration _No response_ ### Docker Image customizations _No response_ ### Anything else? After removing the parse-time `aiplatform_v1beta1` imports, the system Dag imports without loading that root package and passes Airflow's generic system Dag imp…