vertexai: promote agent_config_source to GA on reasoning_engine

[slevenick]

Promote spec.source_code_spec.agent_config_source to GA on google_vertex_ai_reasoning_engine.

vertexai: added `spec.source_code_spec.agent_config_source` field to `google_vertex_ai_reasoning_engine` (ga)

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes for commit 3f94787:

Diff report

Your PR generated the following diffs in downstream repositories:

Repository	Diff Link	Changes
google provider	View Diff	4 files changed, 327 insertions(+), 1 deletion(-)
google-beta provider	View Diff	2 files changed, 127 insertions(+), 1 deletion(-)

Test report

Analytics

Total Tests	Passed	Skipped	Affected
113	104	7	2

Affected Service Packages

• vertexai

Learn how VCR tests work

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Step 1: Replaying Mode

Action taken

Found 2 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

View the replaying VCR build log

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Step 2: Recording Mode

Recording Mode	Replaying Rerun	Test Name
✅ Log	✅	TestAccVertexAIReasoningEngine_agentConfigSourceUpdate
❌ Error · Log	-	TestAccVertexAIFeatureOnlineStoreFeatureview_vertexAiFeatureonlinestoreFeatureview_featureRegistry_updated

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.

@slevenick VCR tests complete for 3f94787!

[slevenick]

@modular-magician reassign-reviewer

[github-actions]

Googlers: For automatic test runs see go/terraform-auto-test-runs.

@c2thorn, a repository maintainer, has been assigned to review your changes. If you have not received review feedback within 2 business days, please leave a comment on this PR asking them to take a look.

You can help make sure that review is quick by doing a self-review and by running impacted tests locally.