jobs/buildTarget: added post step cleaning repository

the post step cleans the residuals from the update of the source
revisions.

Signed-off-by: Marc Mattmüller <marc.mattmueller@netmodule.com>

jobs/Jenkinsfile_BuildTarget

@@ -85,6 +85,14 @@ pipeline {
           }
         }
       }
+      post {
+        always {
+          script {
+            common.cleanupRepository("${env.YOCTO_REPO_DIR}")
+          }
+        }
+      }
+
     }
 
     stage('Update SSTATE-CACHE MIRROR') {