pve-post-installer: remove Nag-File if already exist

[luckman212]

✍️ Description

This updated version of #6087 does not compare hashes or file contents of the dpkg hook script. It simply overwrites the script if "yes" is chosen, or removes the hook script if "no" is selected.

🔗 Related PR / Issues

• Proxmox VE Post Install no-nag-script on 8.4.5 does not disable subscription nag #6078
• hash check for /etc/apt/apt.conf.d/no-nag-script #6087

✅ Prerequisites (X in brackets)

• Self-review completed – Code follows project standards.
• Tested thoroughly – Changes work as expected.
• No security risks – No hardcoded secrets, unnecessary privilege escalations, or permission issues.

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🛠️ Type of Change (X in brackets)

• 🐞 Bug fix – Resolves an issue without breaking functionality.
• ✨ New feature – Adds new, non-breaking functionality.
• 💥 Breaking change – Alters existing functionality in a way that may require updates.
• 🆕 New script – A fully functional and tested script or script set.
• 🌍 Website update – Changes to website-related JSON files or metadata.
• 🔧 Refactoring / Code Cleanup – Improves readability or maintainability without changing functionality.
• 📝 Documentation update – Changes to README, AppName.md, CONTRIBUTING.md, or other docs.