Resolve "Fetch available parameters directly from GKE when creating a cluster"

What does this MR do?

Adds dropdowns to the CI -> GKE Cluster creation form, using the available projects, zones, and machine types available to an authenticated Google Cloud Platform user.

Are there points in the code the reviewer needs to double check?

No.

Why was this MR needed?

To improve the user experience of the GKE cluster creation. Currently, you have to manually view all options in the GCP console, and manually enter in values for project ID, zone, and machine type.

Screenshots

Before

After

Demo

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• [ ] Documentation created/updated
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

Closes #38759 (closed)