jenkinsfile: use submodule update

Change-Id: I19d5e7550dc7101cfa5c0edbc03812a06232e014

extras/ci/client-qt-gnulinux/Jenkinsfile

@@ -55,9 +55,9 @@ pipeline {
         stage('SCM Checkout') {
             steps {
                 script {
-                    // Checkout jami-project to obtain daemon/LRC/client-qt repositories
                     sh """
-                        ./build.py --init
+                        git rev-parse HEAD
+                        git submodule update --init --recursive
                     """
                 }
             }