Use ubuntu1604-basebuild-4c-4g for portal-sdk

The current portal-sdk jobs use he 2c-1g build nodes.
The VM is no able to allocate he needed memory to
perform extensive tasks for the release-java-daily job.

Change-Id: I6ff665da00d949dda9befe3d31d3061f0a80ed23
Signed-off-by: Jessica Wagantall <jwagantall@linuxfoundation.org>
diff --git a/jjb/portal/portal-sdk.yaml b/jjb/portal/portal-sdk.yaml
index 24935b1..6839543 100644
--- a/jjb/portal/portal-sdk.yaml
+++ b/jjb/portal/portal-sdk.yaml
@@ -22,3 +22,4 @@
     mvn-settings: 'portal-sdk-settings'
     files: '**'
     archive-artifacts: ''
+    build-node: ubuntu1604-basebuild-4c-4g