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/included/install-kubectl-gcloud.md

@@ -1,21 +0,0 @@
----
-title: "gcloud kubectl install"
-description: "How to install kubectl with gcloud snippet for inclusion in each OS-specific tab."
-headless: true
----
-
-You can install kubectl as part of the Google Cloud SDK.
-
-1. Install the [Google Cloud SDK](https://cloud.google.com/sdk/).
-
-1. Run the `kubectl` installation command:
-
-   ```shell
-   gcloud components install kubectl
-   ```
-
-1. Test to ensure the version you installed is up-to-date:
-
-   ```shell
-   kubectl version --client
-   ```