Use ensure-nodejs in Gerrit deployment testing

The install-nodejs role in zuul-jobs has been replaced by
ensure-nodejs, so we should use the new thing if we want our tests
running again.

Change-Id: I196814b616d3b332b2c1d397097c01b5bb0d2aac

playbooks/zuul/gerrit/repos.yaml

@@ -1,7 +1,7 @@
 - hosts: all
   roles:
     - ensure-java
-    - role: install-nodejs
+    - role: ensure-nodejs
       node_version: 10
     - ensure-bazelisk
   tasks: