Increase RAM on gui-unit job, otherwise `npm install` will timeout/fail

Change-Id: Id3311bf61b1aa85ff7e7d69534c2810ec1b50a03
diff --git a/jjb/gui-unit.yaml b/jjb/gui-unit.yaml
index 8b9a68b..9c9e30f 100644
--- a/jjb/gui-unit.yaml
+++ b/jjb/gui-unit.yaml
@@ -36,7 +36,8 @@
           choosing-strategy: gerrit
           jenkins-ssh-credential: '{jenkins-ssh-credential}'
 
-    node: '{build-node}'
+    # `npm install` fails on 1Gb RAM
+    node: 'ubuntu16.04-basebuild-1c-2g'
     project-type: freestyle
     concurrent: true