Fix GenAIGenerativeModelHook ignoring Airflow connection credentials

[srchilukoori]

Description

GenAIGenerativeModelHook.get_genai_client() constructs a genai.Client without passing credentials, causing it to fall back to Application Default Credentials (ADC) even when gcp_conn_id is set to an explicit service-account connection. Users in environments without ADC (e.g. Docker containers, on-premise) receive DefaultCredentialsError at runtime.

The fix passes self.get_credentials() to genai.Client, which is the same pattern used by every other Google provider hook (GCS, BigQuery, Vertex AI, etc.).

Fixes #65709

Changes

• providers/google/src/airflow/providers/google/cloud/hooks/gen_ai.py: Pass credentials=self.get_credentials() to genai.Client in GenAIGenerativeModelHook.get_genai_client().
• providers/google/tests/unit/google/cloud/hooks/test_gen_ai.py: Add test_get_genai_client_passes_connection_credentials to assert credentials from the connection are forwarded to the client.

Root Cause

# Before — credentials omitted, ADC used regardless of gcp_conn_id
def get_genai_client(self, project_id: str, location: str):
    return genai.Client(
        vertexai=True,
        project=project_id,
        location=location,
    )

# After — honours the configured Airflow connection
def get_genai_client(self, project_id: str, location: str):
    return genai.Client(
        vertexai=True,
        project=project_id,
        location=location,
        credentials=self.get_credentials(),
    )

---

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

• Yes Claude

---

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[boring-cyborg]

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[shahar1]

Great catch, thank you!

[srchilukoori]

@shahar1 please approve again, I pushed an empty rebase to rerun a failing provider test

[srchilukoori]

@shahar1 please approve again, I pushed an empty rebase to rerun a failing provider test

@shahar1 I don't see an option to merge, could you start it please. Thank you.

[boring-cyborg]

Awesome work, congrats on your first merged pull request! You are invited to check our Issue Tracker for additional contributions.

[shahar1]

@shahar1 please approve again, I pushed an empty rebase to rerun a failing provider test

@shahar1 I don't see an option to merge, could you start it please. Thank you.

Merging is enabled only for committers :)
I merged it, thanks for your contribution!