Prepare repo for global-jjb v0.25.0

Prepare repo for global-jjb v0.25.0

Global JJB now has non-JJB YAML configuration and requires action on the
ci-management repo when upgrading to this version of Global JJB to
prevent JJB from picking up these YAMLs as config. Follow the
instructions below BEFORE upgrading globall-jjb:

cd <git-root>
git mv jjb/global-jjb global-jjb
mkdir jjb/global-jjb
ln -s ../../global-jjb/shell jjb/global-jjb/shell
ln -s ../../global-jjb/jjb jjb/global-jjb/jjb
git add jjb/global-jjb
git commit -sm "Prepare repo for global-jjb v0.25.0"

Git diff confirms no changes.
diff -bur . /tmp/releng/job_output/

Change-Id: I6d7239b8bab8ef08368f833d9a64cd94a824b158
Signed-off-by: Aric Gardner <agardner@linuxfoundation.org>