Merge pull request #10964 from hetong07/update-kubectl

Update powershell script to install kubectl ver 1.20 on jenkins.

hack/jenkins/windows_integration_test_docker.ps1

@@ -15,6 +15,7 @@
 mkdir -p out
 
 (New-Object Net.WebClient).DownloadFile("https://github.com/medyagh/gopogh/releases/download/v0.6.0/gopogh.exe", "C:\Go\bin\gopogh.exe")
+(New-Object Net.WebClient).DownloadFile("https://dl.k8s.io/release/v1.20.0/bin/windows/amd64/kubectl.exe", "C:\Program Files\Docker\Docker\resources\bin\kubectl.exe")
 
 gsutil.cmd -m cp gs://minikube-builds/$env:MINIKUBE_LOCATION/minikube-windows-amd64.exe out/
 gsutil.cmd -m cp gs://minikube-builds/$env:MINIKUBE_LOCATION/e2e-windows-amd64.exe out/