Remove macos-13 from codeql workflow

[mbg]

Removes macos-13 from the codeql workflow. macos-13 runners will be removed by 4 December and brownouts have started for them, which are now causing this workflow to fail.

Risk assessment

For internal use only. Please select the risk level of this change:

• Low risk: Changes are fully under feature flags, or have been fully tested and validated in pre-production environments and are highly observable, or are documentation or test only.

Which use cases does this change impact?

CI only.

How did/will you validate this change?

CI

If something goes wrong after this change is released, what are the mitigation and rollback strategies?

• Rollback - Change can only be disabled by rolling back the release or releasing a new version with a fix.

How will you know if something goes wrong after this change is released?

CI failures.

Merge / deployment checklist

• Confirm this change is backwards compatible with existing workflows.
• Consider adding a changelog entry for this change.
• Confirm the readme and docs have been updated if necessary.

[Copilot]

Pull Request Overview

This PR removes the macos-13 runner from the test matrix in the CodeQL workflow, reducing the macOS testing platforms from three versions (13, 14, 15) to two (14, 15).

• Removed macos-13 from the OS matrix in the analyze-javascript job