Instance type M6 and Volume gp3, AMI update to Amazon Linux 2 2.0.20230628.

[matafc]

Changes

• Updates the volume type for the bastion and container instances to gp3, from gp2.
• Defines m6 type instances as EBS optimized, per https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSOptimized.html . This will allow us to update the instances to m6i
• Sets the MaxBatchSize for AutoscalingRollingUpdate to 20. This should reduce resource contention or API Rate Limit exceeded type errors when applying Cloudformation changes.
• Also including the latest AMI update so our instances will remain compliant. Details at the section below

This has been tested on a local instance of Barcelona with the sre-sandbox AWS account.

How to roll out

We can update the instance type and volume type at the same time. Both changes require a bcn district apply, and Cloudformation change set execution. These steps will allow you to only perform it once.

• Merge and confirm that this PR's changes has been deployed to Barcelona.
• bcn api patch /districts/:district_name '{ "cluster_instance_type": "m6i.large"}' # replace :district_name
• bcn district apply :district_name
• Review and execute the Cloudformation changeset that was produced.

AMI Update

This PR will also update the AMIs of the container instances as described in this guide:

Release notes

Amazon ECS-optimized AMIs - Amazon Elastic Container Service

ECS AMI SSM path: https://ap-northeast-1.console.aws.amazon.com/systems-manager/parameters/aws/service/ecs/optimized-ami/amazon-linux-2/recommended/image_id/description?region=ap-northeast-1 https://ap-northeast-1.console.aws.amazon.com/systems-manager/parameters/aws/service/ecs/optimized-ami/amazon-linux-2/recommended/description?region=ap-northeast-1

And it also updates the AMI for the bastion image.

Bastion AMI SSM path: https://ap-northeast-1.console.aws.amazon.com/systems-manager/parameters/aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2/description?region=ap-northeast-1

[degikko]

@essa can you help us review this PR, please?