Merge branch 'stable-3.9'

* stable-3.9:
  Don't scan gerrit_index.config for current version when no Lucene
  Listen to OnlineUpgradeListener.onSuccess event
  Improve visibility of the integration tests
  Implement changes indexes lock files check
  Introduce the changes index health check stub
  Format using google-java-format

Change-Id: I601ed267978fd1511fde1dfe5f3cd6d2044ee479