Resolve "Fix GKE wording"

What does this MR do?

This MR changes two sentences for CI/CD > Cluster page, to make them correct from a technical point of view.

ClusterIntegration|Removing cluster integration will remove the cluster configuration you have added to this project. It will not delete your project.

is now

ClusterIntegration|Removing cluster integration will remove the cluster configuration you have added to this project. It will not delete your cluster on Google Container Engine.

and

ClusterIntegration|A %{link_to_container_project} must have been created under this account

is now

ClusterIntegration|This account must have permissions to create a cluster in the %{link_to_container_project} specified below

Since these sentences are localized, it also changes them in the locale files.

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

Why was this MR needed?

Current wording is technically incorrect.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #39648 (closed)