Refactored all pipelines branches to external soft param

Change-Id: I3e451815029227f287aa1575099b0cd25b72433d
diff --git a/jenkins/client/job/debian/packages/testing.yml b/jenkins/client/job/debian/packages/testing.yml
index c7ecf98..f150f80 100644
--- a/jenkins/client/job/debian/packages/testing.yml
+++ b/jenkins/client/job/debian/packages/testing.yml
@@ -17,6 +17,7 @@
             scm:
               type: git
               url: "${_param:jenkins_gerrit_url}/mk/mk-pipelines"
+              branch: "${_param:jenkins_pipelines_branch}"
               credentials: "gerrit"
               script: build-debian-packages-{{build}}.groovy
             trigger: