Updated to gemini-3.5-flash in vertex AI reasoning engine tests

[melinath]

This should fix some vertex AI test failures (like TestAccVertexAIReasoningEngine_memoryGenerationTriggerUpdate):

Error creating ReasoningEngine: googleapi: Error 400: Gemini 2.5 models are not supported. Use `gemini-3.5-flash` instead.

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[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes for commit f3ea38c:

Diff report

Your PR generated the following diffs in downstream repositories:

Repository	Diff Link	Changes
google provider	View Diff	3 files changed, 9 insertions(+), 9 deletions(-)
google-beta provider	View Diff	3 files changed, 10 insertions(+), 10 deletions(-)
Open in Cloud Shell	View Diff	1 file changed, 1 insertion(+), 1 deletion(-)

Test report

Analytics

Total Tests	Passed	Skipped	Affected
128	109	11	8

Affected Service Packages

• vertexai

Learn how VCR tests work

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Step 1: Replaying Mode

Action taken

Found 8 affected test(s) by replaying old test recordings. Starting RECORDING based on the most recent commit.

Click here to see the affected tests

• TestAccVertexAIFeatureOnlineStoreFeatureview_vertexAiFeatureonlinestoreFeatureview_featureRegistry_updated
• TestAccVertexAIReasoningEngine_agentConfigSourceUpdate
• TestAccVertexAIReasoningEngine_customizationConfigsUpdate
• TestAccVertexAIReasoningEngine_memoryGenerationTriggerUpdate
• TestAccVertexAIReasoningEngine_vertexAiReasoningEngineContextSpecExample
• TestAccVertexAIReasoningEngine_vertexAiReasoningEngineFullExample
• TestAccVertexAIReasoningEngine_vertexAiReasoningEngineGranularTtlExample
• TestAccVertexAIReasoningEngine_vertexAiReasoningEngineUpdate

View the replaying VCR build log

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Step 2: Recording Mode

Recording Mode	Replaying Rerun	Test Name
✅ Log	✅	TestAccVertexAIReasoningEngine_agentConfigSourceUpdate
✅ Log	✅	TestAccVertexAIReasoningEngine_customizationConfigsUpdate
✅ Log	✅	TestAccVertexAIReasoningEngine_memoryGenerationTriggerUpdate
✅ Log	✅	TestAccVertexAIReasoningEngine_vertexAiReasoningEngineContextSpecExample
✅ Log	✅	TestAccVertexAIReasoningEngine_vertexAiReasoningEngineGranularTtlExample
❌ Error · Log	-	TestAccVertexAIFeatureOnlineStoreFeatureview_vertexAiFeatureonlinestoreFeatureview_featureRegistry_updated
❌ Error · Log	-	TestAccVertexAIReasoningEngine_vertexAiReasoningEngineFullExample
❌ Error · Log	-	TestAccVertexAIReasoningEngine_vertexAiReasoningEngineUpdate

Caution

Issues requiring attention before PR completion

🔴 Initial Recording Failed: Some tests failed during the recording step. See the table above for details.

Please address these issues to complete your PR. If you believe these detections are incorrect or unrelated to your change, please raise the concern with your reviewer.

View the recording VCR build log or the debug logs folder for detailed results.

@melinath, @SirGitsalot VCR tests complete for f3ea38c!