Implement creating the instances via nodegroups.

[gthao313]

I recommend creating the instances via nodegroups via eksctl configuration files. You can specify any arbitrary setting you want. So you can have the node-labels set as a Bottlerocket settings directly.

According to Erikson's suggestion on improving old version BR instance, we think it's better to create nodes via nodegroups.

Meanwhile, Currently Integration test needs users to input the old AMIs --instance-id. We can have a functionality about getting AMI version which gets fetched via SSM. Let user choose the BR version they want and Integration test to get the AMI.