update job to run every 6 hours

Change-Id: Ie3b31b682c58ce3cdc7d9842825f25ed2b2a2581
diff --git a/jjb/cord-test/nightly-build-pipeline.yaml b/jjb/cord-test/nightly-build-pipeline.yaml
index d654905..ac77fec 100644
--- a/jjb/cord-test/nightly-build-pipeline.yaml
+++ b/jjb/cord-test/nightly-build-pipeline.yaml
@@ -880,7 +880,7 @@
     triggers:
        - timed: |
                  TZ=America/Los_Angeles
-                 H/30 * * * *
+                 H H/6 * * *
 
 - job-template:
     name: 'build_{config-pod}_voltha_{release}_test'