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-linux.md

@@ -22,7 +22,6 @@ The following methods exist for installing kubectl on Linux:
 - [Install kubectl binary with curl on Linux](#install-kubectl-binary-with-curl-on-linux)
 - [Install using native package management](#install-using-native-package-management)
 - [Install using other package management](#install-using-other-package-management)
-- [Install on Linux as part of the Google Cloud SDK](#install-on-linux-as-part-of-the-google-cloud-sdk)
 
 ### Install kubectl binary with curl on Linux
 
@@ -168,10 +167,6 @@ kubectl version --client
 
 {{< /tabs >}}
 
-### Install on Linux as part of the Google Cloud SDK
-
-{{< include "included/install-kubectl-gcloud.md" >}}
-
 ## Verify kubectl configuration
 
 {{< include "included/verify-kubectl.md" >}}