add cleanup script for docker windows machine

hack/jenkins/windows_cleanup_and_reboot_docker.ps1

@@ -0,0 +1,20 @@
+function Jenkins {
+	Get-Process e2e-windows-amd64 2>$NULL
+	if ($?) {
+		return $TRUE
+	}
+	return $FALSE
+}
+
+if (Jenkins) {
+	exit 0
+}
+echo "waiting to see if any jobs are coming in..."
+timeout 30
+if (Jenkins) {
+	exit 0
+}
+echo "doing it"
+docker system prune --all --force
+Get-Process "*Docker Desktop*" | Stop-Process
+shutdown /r

hack/jenkins/windows_cleanup_cron.ps1

@@ -0,0 +1 @@
+Schtasks /create /tn cleanup_reboot /sc HOURLY /tr "Powershell gsutil -m cp gs://minikube-builds/master/windows_cleanup_and_reboot_docker.ps1 C:\Users\jenkins; C:\Users\jenkins\windows_cleanup_and_reboot_docker.ps1"