Migrate EKS CloudFormation node pool template from using NodeAutoScalingInitSize to NodeAutoScalingGroupDesiredCapacity

[pregnor]

Is your feature request related to a problem? Please describe.

Currently we are using NodeAutoScalingInitSize parameter in EKS node pool stack CloudFormation templates as the desired size of the node pool due to historical reasons.

The EKS CloudFormation node pool template officially introduced the NodeAutoScalingGroupDesiredCapacity parameter to implement the same (or rather more generalized) usage for the stack template.

It would eliminate the tech debt of this difference if we could migrate the template to use the new parameter and deprecate the old one.

Note: the solution must be ready to handle reading (listing, retrieving old values) and writing (updating) older (pre-parameter, 1.0.0) templated stacks using the newer template during stack update, and especially must be careful about handling UsePreviousValue scenarios on stacks created from template not containing a newly introduced parameter.

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Additional context

Template versioning is reliable for migration/workaround purposes. Empty/missing/1.0.0 version is lacking NodeAutoScalingGroupDesiredCapacity while from 2.0.0 onward, the template contains this parameter.