Add ability to configure AWS Data Disk backups

We should include backups as a best practice within GET for deploying GitLab instances. We have two ways of accomplishing this:

1. Using the GitLab backup tool
2. Using cloud provider snapshots and backups

While the GitLab backup tool works, it tends to be slow and not very scalable for large instances. Most self-managed deployments instead utilize snapshots for backups. We could bake this into GET with good defaults for frequency and retention.

Stateful content:

• Data Disk EBS Snapshots
  • VM's w/ EBS using DLM - https://aws.amazon.com/blogs/storage/automating-amazon-ebs-snapshot-and-ami-management-using-amazon-dlm/.
  • EKS PV's - Supported! But requires the out of tree EBS drivers - https://aws.amazon.com/blogs/containers/using-ebs-snapshots-for-persistent-storage-with-your-eks-cluster/.

Another benefit of having snapshots for EBS volumes is that it seems to increase the durability (reduce AFR) of EBS volumes: https://odetodata.com/2015/02/relationship-between-aws-ebs-snapshots-and-ebs-volume-failure-rates/.