enable directory deletion in final step

Signed-off-by: Héctor Orón Martínez <hector.oron@collabora.co.uk>
Reviewed-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D7263

Jenkinsfile

@@ -56,7 +56,7 @@ def buildImage(architecture, type, board, debosarguments = "") {
               }
           } finally {
             stage("Cleanup ${architecture} ${type}") {
-              //deleteDir()
+              deleteDir()
             }
           }
         }