Remove Google SDK instructions. (#28165)

* Remove Google SDK instructions.

Ref: https://github.com/kubernetes/website/issues/20232

* Remove Google SDK instructions for MacOS

* Remove Google SDK instructions for Windows

* Delete install-kubectl-gcloud.md

content/en/docs/tasks/tools/install-kubectl-macos.md

@@ -22,7 +22,6 @@ The following methods exist for installing kubectl on macOS:
 - [Install kubectl binary with curl on macOS](#install-kubectl-binary-with-curl-on-macos)
 - [Install with Homebrew on macOS](#install-with-homebrew-on-macos)
 - [Install with Macports on macOS](#install-with-macports-on-macos)
-- [Install on macOS as part of the Google Cloud SDK](#install-on-macos-as-part-of-the-google-cloud-sdk)
 
 ### Install kubectl binary with curl on macOS
 
@@ -149,11 +148,6 @@ If you are on macOS and using [Macports](https://macports.org/) package manager,
    kubectl version --client
    ```
 
-
-### Install on macOS as part of the Google Cloud SDK
-
-{{< include "included/install-kubectl-gcloud.md" >}}
-
 ## Verify kubectl configuration
 
 {{< include "included/verify-kubectl.md" >}}