refactor: AWS cloud-init files

[Harsh9485]

#723

Description

Refactored AWS Linux template to use cloud-init for agent initialization, bringing it to parity with the Azure template pattern.

Key Changes:

• Moved Coder agent initialization from Terraform startup_script to cloud-init configuration
• Added systemd service for Coder agent with proper restart policies and OOM protection
• Implemented cloud-init cloud_final_modules with always frequency to ensure agent starts on every workspace boot
• Added proper user creation and permissions handling via cloud-init

Type of Change

• New module
• New template
• Bug fix
• Feature/enhancement
• Documentation
• Other

Template Information

Path: registry/coder/templates/aws-linux

Testing & Validation

• Tests pass (bun test)
• Code formatted (bun fmt)
• Changes tested locally

Screenshots

[Harsh9485]

I want to mention that when I ran terraform init, the agent_name variable did not exist. So in my template, I removed agent_name.

[matifali]

#723 describes general problem with multiple templates o this PR does not address the issue in whole. I wonder how it is solving that problem for the AWS template?

[Harsh9485]

#723 describes general problem with multiple templates o this PR does not address the issue in whole. I wonder how it is solving that problem for the AWS template?

Oh, my mistake. I wrote closes, but this PR is for the aws-linux template.

I only refactored the code that runs the init script in the AWS VM. I know coder/coder#22664 added a check script, but I made this PR because I think using a cloud-init file is a better way to run the init script in the AWS VM