ci: drop custom CodeQL workflow — default setup already covers python+javascript

The repo has GitHub's default CodeQL setup enabled (it scans python, javascript-typescript, ruby and actions on every PR). The custom .github/workflows/codeql-analysis.yml runs a second 'Analyze (python|javascript)' matrix on the same commit; GitHub rejects its SARIF upload with 'CodeQL analyses from advanced configurations cannot be processed when the default setup is enabled', so the custom workflow has been failing on every PR since the default setup was turned on.

Default setup already covers the same language set (and more), so deleting the custom workflow leaves us with one working CodeQL run instead of one working + one always-red.

Author: claude