Refactored all pipelines branches to external soft param

Change-Id: I3e451815029227f287aa1575099b0cd25b72433d
diff --git a/jenkins/client/job/docker/init.yml b/jenkins/client/job/docker/init.yml
index 63c3f27..c5f7d44 100644
--- a/jenkins/client/job/docker/init.yml
+++ b/jenkins/client/job/docker/init.yml
@@ -57,6 +57,7 @@
             scm:
               type: git
               url: "${_param:jenkins_gerrit_url}/mk/mk-pipelines"
+              branch: "${_param:jenkins_pipelines_branch}"
               credentials: "gerrit"
               script: docker-build-image-pipeline.groovy
             trigger: