feat(eks): update nodegroup gpu check (#32715)

### Issue # (if applicable)

Closes #31347.

### Reason for this change


The motivating bug is that you cannot add a combo of g5 and a g6 as instance classes onto the same node group or else the following error will be thrown: `instanceTypes of different architectures is not allowed`.

### Description of changes


* (eks) Fixes the `isGpuInstanceType` check
  * G6/G6E instance classes will now be recognized as GPU instance types so those different types can be used together for a multi instance type managed node group

### Description of how you validated changes


Wrote unit tests for the `isGpuInstanceType` function

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

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Duplicate of #31445, originally authored by @ [AlexKaracaoglu](https://github.com/AlexKaracaoglu)

Co-authored-by: Alex Karacaoglu AlexKaracaoglu@users.noreply.github.com

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: paulhcsun