[AETHER-602] CI job for the release of TOST artifacts

The pipeline updates the <version> tag according to the
given repo, and pushes two new Gerrit changes:

1) With version the given ${version} (e.g., 1.0.0)
2) With ${nextVersion}-SNAPSHOT (e.g., 1.1.0-SNAPSHOT)

Users must manually approve and merge these changes on Gerrit. Once merged,
it's up to the maven-publish and version-tag jobs to complete the release.

Change-Id: Id52797193912c2f72f6450c0c70108fda0065936
diff --git a/jjb/repos/tost-onos.yaml b/jjb/repos/tost-onos.yaml
index b581054..802309c 100644
--- a/jjb/repos/tost-onos.yaml
+++ b/jjb/repos/tost-onos.yaml
@@ -12,6 +12,9 @@
       - 'publish-tost-onos-jobs':
           branch-regexp: '{supported-branches-regexp}'
 
+      - 'release-tost-onos-jobs':
+          branch-regexp: '{supported-branches-regexp}'
+
 - job-group:
     name: 'verify-tost-onos-jobs'
 
@@ -34,3 +37,8 @@
           maintainers: 'charles@opennetworking.org, pier@opennetworking.org'
           build-timeout: 30
           dependency-jobs: 'version-tag'
+
+- job-group:
+    name: 'release-tost-onos-jobs'
+    jobs:
+      - 'artifact-release'
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