fix(ai): Update code execution and URL context doc comments to reflect they are public now

[hsubox76]

Update code execution and URL context features to reflect that they are generally available and no longer public preview. This happened some time ago and we are catching up in the docs.

Also removed a stray sentence referencing the wrong feature.

[changeset-bot]

🦋 Changeset detected

Latest commit: 552b701

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@firebase/ai	Patch
firebase	Patch

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[github-actions]

Vertex AI Mock Responses Check ⚠️

A newer major version of the mock responses for Vertex AI unit tests is available. update_vertexai_responses.sh should be updated to clone the latest version of the responses: v16.2

[gemini-code-assist]

Code Review

This pull request promotes the code execution and URL context features from beta to public (GA) status. The changes include updating the changeset, API review files, documentation, and source code JSDoc tags. A copy-paste error was identified in both the generated documentation and the source JSDoc for CodeExecutionTool, where it incorrectly refers to Google Search configuration instead of code execution configuration.