Upgrade global-jjb to v0.52.0-4-g769456c

Pick up recent change that adds weekly cron to docker merge template

Signed-off-by: Lott, Christopher (cl778h) <cl778h@att.com>
Change-Id: Ia20338f3d03d56361d1b4a25e2de59dab01b1949

diff --git a/global-jjb b/global-jjb
index b55451a..769456c 160000 (submodule)
--- a/global-jjb
+++ b/global-jjb
@@ -1 +1 @@
-Subproject commit b55451a53da28d40c62de5cae462302a32fe4c31
+Subproject commit 769456c55e5b9f92fe1b8c10088bc4ac2dde79c8