Follow-up from "Move all cluster create documentation to new page"

The following discussion from !18233 (merged) should be addressed:

• @tauriedavis started a discussion:

  I don't think we need separate instructions for GKE vs. EKS. The GKE instructions here worked for me for an EKS cluster. Can we simplify and just have one method? 🤔

  cc @danielgruesso