exporting Snow node AMI to S3 fails when following the build guide

**What happened**:
[When following the docs to build a Snow node image](https://anywhere.eks.amazonaws.com/docs/osmgmt/artifacts/#build-snow-node-images) (step 5-7) you get the error when you want to export your newly built AMI to a raw image to S3:
`An error occurred (NotExportable) when calling the ExportImage operation: The image ID provided (ami-xzy123) is a marketplace AMI and is not exportable.`
This export needs to work so you can later upload your image to your snow device.

**What you expected to happen**:
My AMI be exported as a RAW image to s3.

**How to reproduce it (as minimally and precisely as possible)**:
Follow step 1-7 in the following guide: https://anywhere.eks.amazonaws.com/docs/osmgmt/artifacts/#build-snow-node-images

**Anything else we need to know?**:
Solved by using the following Ubuntu AWS account ID: `099720109477`[1] instead of `679593333241` (AWS Marketplace Account ID) in `ami.json`. This make sure you don't use a marketplace AMI which is not allowed the be exported[2].

[1] https://ubuntu.com/server/docs/cloud-images/amazon-ec2
[2] https://docs.aws.amazon.com/vm-import/latest/userguide/vmexport_image.html#limits-image-export

**Environment**:
- EKS Anywhere Release: -
- EKS Distro Release: -

Start with the Snow node image build guide, especially steps 1-7 and the ami.json example. Verify the Ubuntu account ID used there against the linked Ubuntu and AWS export documentation, then update the guide so the resulting AMI can be exported as a RAW image to S3 without the marketplace-AMI error.

Written by the indexing model from the issue text.