perf: Improve Windows packer examples

[iataylor]

Changes made per the issue here https://github.com/philips-labs/terraform-aws-github-runner/issues/4248.

• The SSH packer provisioner is much more reliable, and much quicker, than the WinRM provisioner originally used.
• The disk size should be increased from 30 -> 100 gigs by default for Windows instances, as we fill most of that space just by creating the image with basic dependencies.
• Adding AWS account variable for the ami_users parameter for amazon-ebs module.
• Changing the way we install chocolatey and the cloudwatch-agent from Invoke-WebRequest to System.Net.WebClient due to slowness issues during builds with the former.
• Removing InitializeInstance in Windows Server 2022. Not appropriate for Server 2022 (only 2016 and 2019), so I pulled it out. Not necessary either, as my runners run totally fine without it.

That should be most of it.

[iataylor]

I updated this to a larger instance for better build times. If we'd rather default to smaller in the example, I can replace it.

[iataylor]

We could leave this parameterized. I've just set this to 100 gigs hardcoded.

[iataylor]

All tests passed locally.

[npalm]

The CI checks for packer are failing. I will mark the PR as draft. Please feel free to mark it ready for review when you are.

[stuartp44]

The CI checks are failing on formatting, just do a packer fmt and it should then actually test the changes @iataylor.