Python: Fix GoogleAI validation: skip API key check when using Vertex AI

[veeceey]

Summary

Fixes #13483 - GoogleAIChatCompletion now correctly skips API key validation when use_vertexai=True.

Changes

• Updated API key validation in GoogleAIChatCompletion constructor to only require api_key when use_vertexai is False
• Added unit test to verify initialization succeeds with Vertex AI mode without an API key

Test Plan

• Added test_google_ai_chat_completion_init_with_vertexai_without_api_key to verify the fix
• Existing tests ensure API key is still required when use_vertexai=False
• Existing tests ensure project ID is required when use_vertexai=True

The validation logic now correctly differentiates between:

• Vertex AI mode (use_vertexai=True): Requires project_id, API key is optional (uses ADC)
• Standard mode (use_vertexai=False): Requires api_key

[veeceey]

Hi team -- friendly ping! This PR has been open for a couple of days without review. Would love any feedback when you get a chance. Thanks!

[moonbox3]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
connectors/ai/google/google_ai/services
google_ai_chat_completion.py	143	13	90%	113–114, 147, 151, 168, 173, 189, 193, 215, 220–221, 236, 238
TOTAL	28147	4821	82%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3834	23 💤	0 ❌	0 🔥	1m 46s ⏱️

[eavanvalkenburg]

@veeceey there is a check failure, too long line in the new test, please fix!

[veeceey]

Fixed! The long line in the test has been wrapped to comply with the line length limit. See commit f7edfe4. All tests pass and ruff is clean. Thanks for catching that!

[PrathamAditya]

@veeceey , I have already created the PR for this 😂, just a little update was needed from my side.

[veeceey]

Hey @PrathamAditya, sorry about the overlap! I didn't see a PR for this when I started. If yours is further along or the maintainers prefer it, happy to close mine. @eavanvalkenburg let me know which one you'd like to go with!

[PrathamAditya]

@veeceey No problem! Looking forward to contribute together.

[veeceey]

Hey @eavanvalkenburg, just checking in -- this PR is approved and CI is green. Could you merge when you get a chance? Happy to rebase if needed. Thanks!

[veeceey]

Thanks for the approval! Is there anything else needed to get this merged?

[veeceey]

Rebased on latest main to get up to date. CI should be green shortly. @eavanvalkenburg would be great to get this merged when you have a sec -- thanks!

[moonbox3]

CI may still fail. We're trying to get another PR in (MacOS runners are being super slow). Will get this in soon. Thanks for your patience.

[veeceey]

thanks for the update! no rush at all, appreciate you keeping me in the loop.

[veeceey]

Rebased on latest main to resolve the merge conflict. Kept both the new cloud_region validation from upstream and our Vertex AI API key fix. CI should be running now.

[moonbox3]

@veeceey are we missing files? I only see a test file changed in the latest commits.

[moonbox3]

Hi @veeceey, this was fixed via #13607.