Fix Ansible lint errors, using Duo Custom Rules and Agentic Chat

This code change updates an automated GitLab server setup script to follow modern best practices and improve reliability. The main changes include:

Standardization: All commands now use fully-qualified module names (like ansible.builtin.apt instead of just apt) which makes the script more explicit and prevents potential conflicts.

Boolean consistency: Changed all yes/no values to true/false throughout the script, creating a uniform format that's easier to read and maintain.

Minor cleanup: Removed trailing whitespace and made formatting more consistent across the file.

Module updates: Updated one firewall module to use a community-maintained version instead of a built-in one.

These changes don't alter what the script actually does - it still performs the same GitLab installation and configuration tasks. Instead, they modernize the code structure to align with current Ansible standards, making it more maintainable and less prone to issues in future versions. Think of it like updating the grammar and formatting of a document while keeping the same content and meaning.