Download plugins from archive-ci.gerritforge.com

Gerrit v2.16 is now EOL and all plugins need to be downloaded
from the archive site.

Change-Id: I37908a0453bc54b1ca1f133b66ade31930397601
diff --git a/src/test/docker/gerrit/Dockerfile b/src/test/docker/gerrit/Dockerfile
index 537cb3c..1511350 100644
--- a/src/test/docker/gerrit/Dockerfile
+++ b/src/test/docker/gerrit/Dockerfile
@@ -2,7 +2,7 @@
 
 ENV GERRIT_BRANCH=stable-2.16
 
-ENV GERRIT_CI_URL=https://gerrit-ci.gerritforge.com/job
+ENV GERRIT_CI_URL=https://archive-ci.gerritforge.com/job
 
 USER root