feat: (IAC-925) Added an option in IAC AWS to use a single AZ

[anthoday]

Improvements

The 'enable_multi_zone' flag has been implemented to enable customers to deploy EKS worker nodes across multiple availability zones in AWS. Additionally, the option to deploy EKS worker nodes into a single availability zone has been added.

Changes

• When 'enable_multi_zone' is set to 'true', the EKS cluster will be deployed across multiple availability zones defined in the 'module.vpc.private_subnets' list.
• When 'enable_multi_zone' is set to 'false', the EKS cluster will only be deployed in the first availability zone in the 'module.vpc.private_subnets' list.

Testing

See internal ticket for details and test artifacts:

Scenario	Provider	.tfvars file	k8s Version	Multi-Zone Flag 'false' : Results	Multi-Zone Flag 'true' : Results
1	AWS	sample-input.tfvars	1.23	Using the AWS Console - validated that all EKS nodes are deployed in the same zone.	Using the AWS Console - validated that all EKS nodes are deployed in multiple zones.
2	AWS	sample-input-connect.tfvars	1.23	Using the AWS Console - validated that all EKS nodes are deployed in the same zone.	Using the AWS Console - validated that all EKS nodes are deployed in multiple zones.
3	AWS	sample-input-custom-data.tfvars	1.23	Using the AWS Console - validated that all EKS nodes are deployed in the same zone.	Using the AWS Console - validated that all EKS nodes are deployed in multiple zones.
4	AWS	sample-input-defaults.tfvars	1.23	Using the AWS Console - validated that all EKS nodes are deployed in the same zone.	Using the AWS Console - validated that all EKS nodes are deployed in multiple zones.
5	AWS	sample-input-gpu.tfvars	1.23	Using the AWS Console - validated that all EKS nodes are deployed in the same zone.	Using the AWS Console - validated that all EKS nodes are deployed in multiple zones.
6	AWS	sample-input-ha.tfvars	1.23	Using the AWS Console - validated that all EKS nodes are deployed in the same zone.	Using the AWS Console - validated that all EKS nodes are deployed in multiple zones.
7	AWS	sample-input-minimal.tfvars	1.23	Using the AWS Console - validated that all EKS nodes are deployed in the same zone.	Using the AWS Console - validated that all EKS nodes are deployed in multiple zones.
8	AWS	sample-input-singlestore.tfvars	1.23	Using the AWS Console - validated that all EKS nodes are deployed in the same zone.	n/a

[jarpat]

Keeping this PR open for now, but pulling the changes/diffs into a new working branch (IAC-1174) based off staging. This seems easier than trying to rebase it.

[jarpat]

Superseded by #234