JJB cleanups for VOLTHA.

Misc/
  o yaml lint clenaups
  o Remove prototype voltha-2.{9,10,11} job placeholders.
  o Replace mainatiner email address (Matteo) with build system group.

Change-Id: I37e1175f56042632753b75c849dbaf07f74bd284
diff --git a/jjb/verify/voltha-system-tests.yaml b/jjb/verify/voltha-system-tests.yaml
index 9a8cc35..8b442db 100644
--- a/jjb/verify/voltha-system-tests.yaml
+++ b/jjb/verify/voltha-system-tests.yaml
@@ -10,22 +10,12 @@
           build-node: 'ubuntu18.04-basebuild-4c-8g'
           branch-regexp: '{all-branches-regexp}'
       - 'verify-voltha-system-tests-jobs-voltha-2.8':
-          build-node:  'ubuntu18.04-basebuild-4c-8g'
+          build-node: 'ubuntu18.04-basebuild-4c-8g'
           name-extension: '-voltha-2.8'
           override-branch: 'voltha-2.8'
           branch-regexp: '^voltha-2.8$'
-      - 'verify-voltha-system-tests-jobs-voltha-2.9':
-          build-node:  'ubuntu18.04-basebuild-4c-8g'
-          name-extension: '-voltha-2.9'
-          override-branch: 'voltha-2.9'
-          branch-regexp: '^voltha-2.9$'
-      - 'verify-voltha-system-tests-jobs-voltha-2.10':
-          build-node:  'ubuntu18.04-basebuild-4c-8g'
-          name-extension: '-voltha-2.10'
-          override-branch: 'voltha-2.10'
-          branch-regexp: '^voltha-2.10$'
       - 'verify-voltha-system-tests-jobs-master':
-          build-node:  'ubuntu18.04-basebuild-4c-8g'
+          build-node: 'ubuntu18.04-basebuild-4c-8g'
           branch-regexp: '^master$'
 
 - job-group:
@@ -46,18 +36,6 @@
           pipeline-script: 'voltha/voltha-2.8/bbsim-tests.groovy'
 
 - job-group:
-    name: 'verify-voltha-system-tests-jobs-voltha-2.9'
-    jobs:
-      - 'voltha-patch-test':
-          pipeline-script: 'voltha/voltha-2.9/bbsim-tests.groovy'
-
-- job-group:
-    name: 'verify-voltha-system-tests-jobs-voltha-2.10'
-    jobs:
-      - 'voltha-patch-test':
-          pipeline-script: 'voltha/voltha-2.10/bbsim-tests.groovy'
-
-- job-group:
     name: 'verify-voltha-system-tests-jobs-master'
     jobs:
       - 'voltha-patch-test':