Fix e2e test

Author: hakman

test/e2e-install.sh

@@ -79,6 +79,11 @@ function install-npd() {
   echo "Starting NPD systemd service."
   systemctl daemon-reload
   systemctl start node-problem-detector.service
+
+  # Wait for Prometheus
+  while ! --output /dev/null --silent --head --fail http://localhost:20257/metrics; do
+    sleep 1 && echo -n .
+  done
 }
 
 function main() {