Make Vertex AI evaluation optional to avoid litellm bloat

[Vamsi-klu]

Problem

apache-airflow-providers-google pulled google-cloud-aiplatform[evaluation] into the base provider install. That extra brings in evaluation-only dependencies such as litellm, scikit-learn, huggingface-hub, and tokenizers for users who may only need unrelated Google services.

The only code path that needs vertexai.preview.evaluation is Vertex AI model evaluation through GenerativeModelHook.get_eval_task(), GenerativeModelHook.run_evaluation(), and RunEvaluationOperator.

What Changed

• Changed the base dependency to google-cloud-aiplatform>=1.155.0.
• Added an evaluation provider extra that installs google-cloud-aiplatform[evaluation]>=1.155.0.
• Added an import guard that raises AirflowOptionalProviderFeatureException with an install instruction when evaluation APIs are used without the extra.
• Added a provider changelog note for the breaking dependency split.
• Updated generated provider dependency docs and uv.lock.
• Added a follow-up regression test for the missing-extra path and documented the evaluation extra in the Vertex AI operator docs.

Why The Follow-Up Commit Exists

The feedback was correct: the original PR proved the opt-in path but did not directly test the failure mode when the extra is missing, did not document the extra next to RunEvaluationOperator, and left the lockfile inconsistent with the dependency split.

Impact

• Base Google provider installs no longer pull the evaluation dependency stack.
• Users of RunEvaluationOperator or direct Vertex AI evaluation hook methods must install apache-airflow-providers-google[evaluation].
• Users who do not use evaluation APIs should see no runtime behavior change.

Fixes: #69323

Testing

• UV_CACHE_DIR=/tmp/uv-cache-69749 uv run --python 3.11 ruff format providers/google/tests/unit/google/cloud/hooks/vertex_ai/test_generative_model_optional_evaluation.py
• UV_CACHE_DIR=/tmp/uv-cache-69749 uv run --python 3.11 ruff check --fix providers/google/tests/unit/google/cloud/hooks/vertex_ai/test_generative_model_optional_evaluation.py
• AIRFLOW_HOME=/tmp/airflow-home-69749 UV_CACHE_DIR=/tmp/uv-cache-69749 uv run --python 3.11 --project providers/google pytest providers/google/tests/unit/google/cloud/hooks/vertex_ai/test_generative_model_optional_evaluation.py --with-db-init -xvs
• Result: 2 passed, 1 warning
• AIRFLOW_HOME=/tmp/airflow-home-69749 UV_CACHE_DIR=/tmp/uv-cache-69749 uv run --python 3.11 --project providers/google --extra evaluation pytest providers/google/tests/unit/google/cloud/hooks/vertex_ai/test_generative_model.py providers/google/tests/unit/google/cloud/operators/vertex_ai/test_generative_model.py -xvs
• Result: 2 passed, 1 warning
• Commit hooks passed for the follow-up commit.

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

• Yes — Codex (GPT-5)

Generated-by: Codex (GPT-5) following the guidelines

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Drafted-by: Codex (GPT-5); reviewed by @Vamsi-klu before posting

[Vamsi-klu]

Reviewers: @shahar1 (google provider CODEOWNER). Breaking change: evaluation extra now optional to avoid litellm bloat. Changelog entry added, provider docs regenerated via update-providers-dependencies.

Fixes #69323

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Drafted-by: Muse Spark 1.1; reviewed by @Vamsi-klu before posting

[github-actions]

uv.lock on main just moved via #69924 ("Support excluding files from common.ai Agent Skills discovery"), commit 663a792 and this PR currently conflicts.

Quickest fix:

git fetch upstream main && git rebase upstream/main
rm uv.lock && uv lock
git add uv.lock && git rebase --continue
git push --force-with-lease

Automated nudge — ignore if you're not ready to rebase. This comment is updated in place on future uv.lock bumps.