Merge branch 'stable-3.0' into stable-3.1

* stable-3.0:
  Set Gerrit to 3.0.16
  Download plugins from archive-ci
  Set Gerrit to 2.16.26
  Set Gerrit to 3.0.15
  Set Gerrit to 2.16.25
  Set Gerrit to 3.0.14
  Set Gerrit to 2.16.24
  Set Gerrit to 2.16.23
  Set Gerrit to 3.0.13

Change-Id: I7135342c134a2ac9231fb3a5dbd78311f1ecdcd2