EKS Workshop - use EC2 Describe Instance Types instead of Spot Instance Advisor

[ruecarlo]

The current qualification of instances is done by filtering aid of Spot Instance Advisor. At the time this was the best way to qualify and filter instances. Now we do have the EC2 Dashboard for describe instances, which is probably better to filter and does not distract with changing frequency of interruptions that might be changing over time... This change over time might cause users to remove instances from the diversified pools just because in the past (when they qualified the instances) they had a high level of interruptions. The goal is still to let capacity-optimized to select the best and more appropriate capacity pools and increase as much as we can the diversification and pools we can tap on for each nodegroup