labs/installing: switch to gcloud compute ssh

So we just need to figure out a command to match ${KUBE_APISERVER_EXTERNAL_IP} with the gce instance name?

Something like could work, WDYT?
```
 gcloud compute instances list --format json | jq '.[] | select (.networkInterfaces[].accessConfigs[].natIP == "${KUBE_APISERVER_EXTERNAL_IP}") | .name'
```