CHEF-29006: Add package-cleanup command documentation

[Aishwarya2001A]

• Add comprehensive documentation page for chef-automate package-cleanup command
• Add YAML command reference with detailed flag descriptions and examples
• Document all 6 usage cases (3 non-verbose + 3 verbose scenarios)
• Include multi-pass cleanup algorithm explanation
• Add best practices, troubleshooting guide, and safety mechanisms
• Document protected packages and whitelist behavior

🔩 Description: What code changed, and why?

⛓️ Related Resources

👍 Definition of Done

👟 How to Build and Test the Change

✅ Checklist

All PRs must tick these:

• I have read the CONTRIBUTING document.
• All commits signed-off for the Developer Certification of Origin.

With occasional exceptions, all PRs from Progress employees must tick these:

• Is the code clear? (complicated code or lots of comments--subdivide and use well-named methods, meaningful variable names, etc.)
• Consistency checked? (user notifications, user prompts, visual patterns, code patterns, variable names)
• Repeated code blocks eliminated? (adapt and reuse existing components, blocks, functions, etc.)
• Spelling, grammar, typos checked? (at a minimum use make spell in any component directory)
• Code well-formatted? (indents, line breaks, etc. improve rather than hinder readability)

All PRs from Progress employees should tick these if appropriate:

• Tests added/updated? (all new code needs new tests)
• Docs added/updated? (all customer-facing changes)

Please add a note next to any checkbox above if you are NOT ticking it.

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[sonarqube-for-infrastructure-prod]

Quality Gate passed

Issues
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0 Fixed issues
0 Accepted issues

Measures
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