clean up folder used as pseudo branches of voltha pipeline-scripts

* delete all folders used as pseudo branches for older voltha releases
  (including the unused playground) since those pipeline-scripts are now
  pulled in from the respective release branches for ci-management and
  are not needed in master anymore
* move all files from pseudo branch jjb/pipeline/voltha/master folder to
  jjb/pipeline/voltha folder to remove the mention of a branch in the
  script repo path
* remove 'master/' from path for all active pipeline scripts
* remove makefile used previously to copy folders as pseudo branches for
  releases

Signed-off-by: Jan Klare <jan.klare@bisdn.de>
Change-Id: Ib2f93ec021d0e12f70d550ccadd812c6408bf1ce
Signed-off-by: Jan Klare <jan.klare@bisdn.de>
diff --git a/jjb/verify/device-management.yaml b/jjb/verify/device-management.yaml
index e6322b5..258e9a7 100644
--- a/jjb/verify/device-management.yaml
+++ b/jjb/verify/device-management.yaml
@@ -21,7 +21,7 @@
           junit-allow-empty-results: true
           build-node: 'ubuntu18.04-basebuild-2c-4g'
       - 'device-management-patch-test':
-          pipeline-script: 'voltha/master/device-management-mock-tests.groovy'
+          pipeline-script: 'voltha/device-management-mock-tests.groovy'
 
 - job-group:
     name: 'publish-device-management-jobs'