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/software-upgrades.yaml b/jjb/software-upgrades.yaml
index f23b929..f8df3f2 100644
--- a/jjb/software-upgrades.yaml
+++ b/jjb/software-upgrades.yaml
@@ -10,7 +10,7 @@
     jobs:
       - 'software-upgrades-test-master':
           name: 'periodic-software-upgrade-test-bbsim'
-          pipeline-script: 'voltha/master/software-upgrades.groovy'
+          pipeline-script: 'voltha/software-upgrades.groovy'
           pipeline-branch: 'master'
           build-node: 'ubuntu18.04-basebuild-8c-15g'
           code-branch: 'master'